diff --git a/sdk/models/replay.go b/sdk/models/replay.go
index fead7f18..72478bbe 100644
--- a/sdk/models/replay.go
+++ b/sdk/models/replay.go
@@ -16,9 +16,10 @@ const maximumAllowedReplayDuration = time.Hour * 24 * 30
 
 // Replay Struct used for posting replay entity.
 type Replay struct {
-	Project  string         `json:"project"`
-	Slo      string         `json:"slo"`
-	Duration ReplayDuration `json:"duration"`
+	Project   string          `json:"project"`
+	Slo       string          `json:"slo"`
+	Duration  ReplayDuration  `json:"duration,omitempty"`
+	TimeRange ReplayTimeRange `json:"timeRange,omitempty"`
 }
 
 type ReplayDuration struct {
@@ -26,6 +27,11 @@ type ReplayDuration struct {
 	Value int    `json:"value"`
 }
 
+type ReplayTimeRange struct {
+	StartDate time.Time `json:"startDate,omitempty"`
+	EndDate   time.Time `json:"endDate,omitempty"` // not supported yet
+}
+
 // ReplayWithStatus used for returning Replay data with status.
 type ReplayWithStatus struct {
 	Project string       `json:"project"`
@@ -72,10 +78,30 @@ var replayValidation = govy.New[Replay](
 		Required(),
 	govy.For(func(r Replay) ReplayDuration { return r.Duration }).
 		WithName("duration").
-		Required().
+		When(
+			func(r Replay) bool {
+				return !isEmpty(r.Duration) || (r.TimeRange.StartDate.IsZero() && isEmpty(r.Duration))
+			},
+		).
 		Cascade(govy.CascadeModeStop).
 		Include(replayDurationValidation).
 		Rules(replayDurationValidationRule()),
+	govy.For(func(r Replay) time.Time { return r.TimeRange.StartDate }).
+		WithName("startDate").
+		When(
+			func(r Replay) bool { return !r.TimeRange.StartDate.IsZero() },
+		).
+		Rules(
+			replayStartTimeValidationRule(),
+			replayStartTimeNotInFutureValidationRule(),
+		),
+	govy.For(func(r Replay) Replay { return r }).
+		Rules(govy.NewRule(func(r Replay) error {
+			if !isEmpty(r.Duration) && !r.TimeRange.StartDate.IsZero() {
+				return errors.New("only one of duration or startDate can be set")
+			}
+			return nil
+		}).WithErrorCode(replayDurationAndStartDateValidationError)),
 )
 
 var replayDurationValidation = govy.New[ReplayDuration](
@@ -98,8 +124,10 @@ func (r Replay) Validate() error {
 }
 
 const (
-	replayDurationValidationErrorCode     = "replay_duration"
-	replayDurationUnitValidationErrorCode = "replay_duration_unit"
+	replayDurationValidationErrorCode         = "replay_duration"
+	replayDurationUnitValidationErrorCode     = "replay_duration_unit"
+	replayDurationAndStartDateValidationError = "replay_duration_or_start_date"
+	replayStartDateInTheFutureValidationError = "replay_duration_or_start_date_future"
 )
 
 func replayDurationValidationRule() govy.Rule[ReplayDuration] {
@@ -116,6 +144,27 @@ func replayDurationValidationRule() govy.Rule[ReplayDuration] {
 	}).WithErrorCode(replayDurationValidationErrorCode)
 }
 
+func replayStartTimeValidationRule() govy.Rule[time.Time] {
+	return govy.NewRule(func(v time.Time) error {
+		duration := time.Since(v)
+		if duration > maximumAllowedReplayDuration {
+			return errors.Errorf("%s duration must not be greater than %s",
+				duration, maximumAllowedReplayDuration)
+		}
+		return nil
+	}).WithErrorCode(replayDurationValidationErrorCode)
+}
+
+func replayStartTimeNotInFutureValidationRule() govy.Rule[time.Time] {
+	return govy.NewRule(func(v time.Time) error {
+		now := time.Now()
+		if v.After(now) {
+			return errors.Errorf("startDate %s must not be in the future", v)
+		}
+		return nil
+	}).WithErrorCode(replayStartDateInTheFutureValidationError)
+}
+
 // ParseJSONToReplayStruct parse raw json into v1alpha.Replay struct with govy.
 func ParseJSONToReplayStruct(data io.Reader) (Replay, error) {
 	replay := Replay{}
@@ -168,3 +217,7 @@ func ValidateReplayDurationUnit(unit string) error {
 	}
 	return ErrInvalidReplayDurationUnit
 }
+
+func isEmpty(duration ReplayDuration) bool {
+	return duration.Unit == "" || duration.Value == 0
+}
diff --git a/sdk/models/replay_test.go b/sdk/models/replay_test.go
index 4b5d8976..4bc08e14 100644
--- a/sdk/models/replay_test.go
+++ b/sdk/models/replay_test.go
@@ -131,6 +131,75 @@ func TestReplayStructDatesValidation(t *testing.T) {
 			isValid:   false,
 			ErrorCode: rules.ErrorCodeRequired,
 		},
+		{
+			name: "correct struct start date",
+			replay: Replay{
+				Project: "project",
+				Slo:     "slo",
+				TimeRange: ReplayTimeRange{
+					StartDate: time.Now().Add(-time.Hour * 24),
+				},
+			},
+			isValid: true,
+		},
+		{
+			name: "only one of duration or start date can be set",
+			replay: Replay{
+				Project: "project",
+				Slo:     "slo",
+				Duration: ReplayDuration{
+					Unit:  "Day",
+					Value: 30,
+				},
+				TimeRange: ReplayTimeRange{
+					StartDate: time.Now().Add(-time.Hour * 24),
+				},
+			},
+			isValid:   false,
+			ErrorCode: replayDurationAndStartDateValidationError,
+		},
+		{
+			name: "start date cannot be in the future",
+			replay: Replay{
+				Project: "project",
+				Slo:     "slo",
+				TimeRange: ReplayTimeRange{
+					StartDate: time.Now().Add(time.Minute * 1),
+				},
+			},
+			isValid:   false,
+			ErrorCode: replayStartDateInTheFutureValidationError,
+		},
+		{
+			name: "use start date without duration",
+			replay: Replay{
+				Project: "project",
+				Slo:     "slo",
+				Duration: ReplayDuration{
+					Unit:  "",
+					Value: 0,
+				},
+				TimeRange: ReplayTimeRange{
+					StartDate: time.Now().Add(-time.Hour * 24),
+				},
+			},
+			isValid: true,
+		},
+		{
+			name: "only one of duration",
+			replay: Replay{
+				Project: "project",
+				Slo:     "slo",
+				Duration: ReplayDuration{
+					Unit:  "Day",
+					Value: 30,
+				},
+				TimeRange: ReplayTimeRange{
+					StartDate: time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC),
+				},
+			},
+			isValid: true,
+		},
 	}
 
 	for _, tt := range tests {