How do you know when did i join Gmail?
Go to "Settings" --> "Forwarding and POP/IMAP". In the "POP Download" section: 1. Status: POP is enabled for all mail that has arrived since xx.xx.20xx. That date shows when you joined gmail.
A forgotten G account is often recovered by the users security question in which only they know the answer and once the question is answered they can then log in again. We provide you with Gmail Login, Gmail Sign In & Gmail Sign Up Tutorials. Learn how recover Gmail account, Password & User name in related link below.