It's your call but if you convert ETH to BTC now ideally by 30 July, after 1st August, you will have both BTC and the new hard-forked coin called Bitcoin Cash (BCC) as a bonus. Whatever amount of BTC you will have before 1st August, you will get the same amount of BCC as a bonus! But keep in mind that the price of BTC and BCC will fluctuate a lot during this time.

Also, if you want the BCC, make sure you keep your BTC in a hardware wallet (ledger nano, trezor) or a software wallet (coinomi, jaxx) your have control over (you have the private keys).

https://medium.com/@jimmysong/bitcoin-cash-what-you-need-to-know-c25df28995cf