In the event of sudden, catastrophic decompression at 35,000 feet, you'll have a half minute to one minute of useful conciousness. Plus factor in all the mayhem in the cabin and the stress. The pilot will be executing an emergency descent to a lower altitude so it may be hard to even stand on your feet.

Flights tend to be quite crowded these days, but I think your best bet would be to find an extra mask as close to the lavatory as possible. Obviously, any free mask and seat will probably be a middle seat.