Marketcap is an extremely flawed way to look at things.

Having a giant supply of coins is an easy way to manipulate the flawed coinmarketcap.  Let's say I create a coin and  have 200 million coins outstanding.  I sell one coin for $100.  Now I have a $20 billion market cap.  That doesn't mean I have a market for my 200 million coins. There may only be one person in the world willing to pay $100 for my coin. (my mom and she doesn't have $20 billion to buy the rest of my coins)

As far as Bitcoin Private...  They're forbidden to announce exchange support early. It's a legal issue.  They've spoken about it in length at every single meetup they've done as it is a very common question they get.  I don't know exactly how far in advance but we will know which exchanges are supporting it. Probably 48 hours or so in advance.  You can safely assume that several will be supporting it as they are taking 50% of the donation mining pool and investing in exchange support.  That's 8812 ZCL so far... plenty to pay exchanges to list it.

Remember the snapshot happens on the 28th but the coin doesn't officially launch until 2 days later.