You have 30 days from the date of your QLE to report it to Thatch and start the plan change process — for example, marrying on January 15 gives you until February 14.
A few nuances:
For loss of other coverage, you can start the process up to 30 days before coverage ends, so there's no gap.
For Medicare, the window runs from 3 months before to 3 months after your 65th birthday.
If you miss the 30-day mark, contact support@thatch.com right away — support can sometimes extend the window up to 58 days after the event (still inside the 60-day federal special enrollment period), but that's handled case-by-case, not guaranteed.