But what kind of proof does OP have? Does list of bitcoin address and rough date when the wallet is created/last serve as valid proof?
Some people were asked for wallet creation date, known used IP address(es) which IMO, not enough proof.But since he'll just ask for the Wallet ID which is useless without the password, I guess blockchain(com) may consider.
IP? I doubt anyone keep history of IP given by their ISP
If you get the chance to talk to the support, show them this.
Web archive might be more solid evidence,
English archive (2012) : https://web.archive.org/web/20120921161220/https://blockchain.info/wallet/login
Non-english archive (2013) : https://web.archive.org/web/20130824214325/https://blockchain.info/wallet/login
Or find best archive by yourself at https://web.archive.org/web/2020*/https://blockchain.info/wallet/login