It looks like the biggest uncertainties will be resolved this Friday, July 21st. With far above 80% support for SegWit2x, August 1st should not matter anymore (as BIP 148 will not trigger).
That would mean between now and Thursday should be the best time to buy.
On the other hand, August 1st is passed around everywhere as the "day of doom." Many uninformed people out there. So maybe wait till July 31st to buy? And will there be any risks left after Segwit is activated later this week?
The key question is: How much FUD will be left in the market after Friday...?
yes, it seems support for segwit2x has reach over 87% today and many miners has started to signaling BIP91. Bitcoin price has recovered and slowly increase, $2310 right now and possibly will continue to rise in the next week after Friday, July 21st. I say, better to buy right now instead of waiting for the end of this month, because segwit will be activated obviously and we will see bitcoin skyrocket again after its implemented.