none can really clear it up because the rules are inconsistent and unclear, have a look at my post 19th feb this thread and others either side of it for interpretations of your situation. See also TSA thread
You on't say if you have a full or 61.75 FAA private - that matters to give you a full answer. Plenty posted here and on the tsa thread about that
In your position (current, assume FAA full private) you'd need 10-15 hours - you could probably get it done in 7-10 days - doing it before you leave would be feasible. You are technically out of visa status but you also get some leeway to pack up and leave so you could do it that way