[ Renting & Real Estate ] Open Question : How long does it take to close on a home contigent upon potential buyer selling their own home first ?

Meaning how long to complete loan closing if say the contigent offer person accepted offer on their home as soon as tomorrow? Would it take 2 months or 1 month? Because contigent offer person would have to close on their home sale first which could take a month minimum then start process on new home…