And Where I will receive my elastic after launch ? that's what I'm trying to understand ....
You will just use the "import private key" function, and the ELC should appear right in the wallet. Alternatively, there will be a "sweep private key" function that moves the ELC from the private key to a new, fresh wallet
(at this point, maybe a question to the community: what way should we go ... sweep only, import only, or both?): This is the reason why you need to backup the private key to the address you sent your donation from.
Once again: you need to backup the private key to the address you sent your donation from!!!!! Please double check which address is the first input in your transaction, this is the important one.For people who have used more sophisticated wallets and do not have a private key but rather a "recovery phrase" or a "mnemonic" there will be an import function as well ... in the beginning at least for a selection of the most famous wallets. More importers will then be created by the community on demand.
As long as the wallet is open source, you can always reconstruct the address generation process from the "recovery phrase" and so recover all addresses and their corresponding private keys. This is trivial.