Tesla has been adjusting policies a bit but I believe there are still basically two phases of the trade-in process. An initial estimate which is good for 7 days and then a final offer which is good for 30 days or 1,000 miles. The final offer is what matters but once the 30 days is up, watch out! People have posted on here about seeing their trade offer drop dramatically even just a day or two after the 30 days. There have also been posts about trade values dropping after the 7 days but I think those are more due to discovered issues e.g., submitted pictures showing cosmetic damage, aftermarket equipment, etc.