How long do you need the bitcoins stay on the bitcoin address, if you can be very specific I may be able to do this.
Example, "I need from 10 May 00:00 to 11 May 23:59 UTC".
The snapshot is taken at this exact moment:
The 5th round will happen on May 10, 2017 at 21:42 UTC (at full moon).
All Bitcoins on the address at that moment counts.
I imagine you accept signed messages via PM, not many (me especially) are willing to post any specific amount of coins held publicly on the thread.
No need to imagine, it's explained already:
If you don't want to post your Bitcoin address/balance in public, send me your address + signature in a private message.If i sign a Coinbase address or any other online wallet, is it possible to linked with you and the Airdrop?
Coinbase is an exchange, not a wallet. If they allow you to sign a message you can join, but since it's an exchange, I doubt you can control the funds on that address.