Hi, apologies for taking so long to get back to you! I just posted your question publicly on a new post:

https://steemit.com/bitcoin/@trending/do-i-need-to-maintain-my-btc-balance-for-bcc-great-question-by-southerncross

Here is what I said:

To those holding BTC at the time of the fork, you'll likely be able to exchange your BTC for other cryptocurrencies immediately after the fork happens. Once the BCC is credited to your exchange account (or your hardware or software wallet now, as many exchanges have now halted BTC withdrawals) you will be able to exchange your BTC (and BCC for that matter) for any other cryptocurrencies that you wish. You do NOT need to maintain your balance, unless there are specific rules for the exchange that you are on, but it seems unlikely in most cases.

To be sure, take a look at the news announcement for your specific exchange regarding the BCC fork. If you don't have your BTC on an exchange, you can still deposit to a hardware or software wallet under your control before tomorrow morning. See this post for more details.
Thanks for the great question @southerncross!