I held BTC on my Nano Ledger during the Bitcoin Diamond fork. Will your service be able to retrieve those?

I'm looking to sell a part of my BTC immediately after the fork to invest in some alts (on Bittrex). I know the BCG will be credited in block 491407, but can anyone tell me how to proceed in the quickest fashion, i.e. can I sell as soon as the block is reached, or should I wait until the next block is reached?

Also, the estimations as to when the block will occur are very different. I've seen them range from 28 to 20 hours from now. Thoughts on that?