Some handicap races use a pursuite-type start, where you are starting at a pre-specified time. iRegatta now has this feature added to the Start View.
Tap the timer button in the lower right corner, and you'll see a view where you can set at what time your start is. If you tap "Save", iRegatta will start counting down to that time.
You can leave iRegatta and come back, and it'll still be counting, but do NOT touch the "Pause" or "Sync" buttons, that would invalidate your start time.
3.07.0 is aailable for Android, while the iOS version is awaiting Apple approval.