Yes if he wants to invest then he can invest in it right now as price is good to make an investment and if segwit gets activated then it can pump the price of bitcoins and at that time it will be very hard to buy bitcoins at higher price so investing in bitcoins now is the best thing to do.
Of course, if you are really for a long term investment in bitcoin. buying anytime is the best bet for you. Although some is waiting for the price to drop before getting, I think if you do this you may missed a big opportunity to gain profit. And regarding the Aug 1 date, we still don't know what's gonna happen, but I speculate that the price will go higher. So don't missed the opportunity, grab some bitcoin now and stash it out for long term.
Values keep on fluctuating but prudency is to hold on to your coins as long as possible. The longer you hold, the bigger is the reward. Probably, the prices will increase after August as well, so there is no harm in buying bitcoins now and stashing them away.