HI!
2 questions!
1) Should I invest my money in crypto NOW or should I wait till 1 aug or till i dips again (if) ?
2) Can I keep altcoins (no bitcoin) on Bittrex during the 1 aug fever ?
You should wait until the price of all of the coins gets big dump or big red. you can try to put your bottom order in the market on your interested coin that gives you the more chance to buy cheap coin.
You can try to keep all of your altcoin in the exchange site, but I think the exchange will get an impact for the bitcoin scaling.