Yes, as hosemary has explained above, you can sign the message at any time adyou want as long as you have the addresséaddress’s private key.

In this specific case, most people will accept a signed message as a proof that you are the one who initiated the transaction. But this is notisn’t always true. Signing a message only meansproves that you know the addresséaddress’s private key, but it doesn’t ...necessarily mean that you are the one who initiated the transaction (it could behave been done by someone else who also knows thethat private key).

Yes, as hosemary has explained above, you can sign the message at any time ad long as you have the addressés private key.

In this specific case, most people will accept a signed message as a proof that you are the one who initiated the transaction. But this is not always true. Signing a message only means that you know the addressés private key but it doesn’t ... that you are the one who initiated the transaction (it could be someone else who also knows the private key).