I made major contributions to a startup and am being offered equity - 11% of total stock. I have been at the company for 2.5 years, and am being offered equity with a 4 year vest, starting 1.5 years ago, which was about the point when equity was offered - I complained, saying that it should start from joining time, 2.5 years and 62.5% now, not 1.5 years and 37.5%. What is reasonable and standard here?
TL;DR: The date they were granted. (Usually, this follows both an offer and acceptance.)
It's not uncommon for a new vesting clock to start when there's a new round of funding coming in, because the investors want to make sure the key people are going to be engaged and incentivized going forward from that point. They don't lower their expectations for how long they want folks engaged based on the person having started earlier. Non-institutional investors may have the same concerns as institutional investors here and use the same vesting strategy to address them.
Primary recognition of the benefits from having had people start earlier or be there longer (so long as it correlates with having gotten more done) is embedded in the valuation (which affects how much founders' shares are diluted in the raise).