Hello, so for receiving the Ignis Airdrop, is it enough to keep the $Nxt in the wallet at the time of the snapshot ?
Or do i have to claim it after ?
Yes, you must hold your NXT in the wallet. Once the ardor platform launched on January 1, 2018, and its off testnet, you must download ardor wallet with the same NXT address and passphrase in order to claim it. You can also find all your answer here
https://www.jelurida.com/ignis-airdrop.