If it's the first time the 800k needs to be proven to come from abroad it cannot be "local money".
The bank needs to give you a paper stating that it was transferred and it needs to prove that it was transferred from abroad which usually implies that you have to do a wire transfer of the full amount.
Just keep in mind, for others, that the rules are different for retirement extension.... (No touch 2 months before or after (keep ,> 800) and no ever below 400)
so the 90 days report is basically showing up to show your presence at immigation.... Which is what he asked and what he has to do at the immigration or virtually online....