If it's a narrow win, we are unlikely to know definitively until they finish counting mail-in ballots which take a while. If Biden wins big, like the polls are forecasting, we'll know so pretty fast, though I'm sure Trump will still hold out for counting of mailed in ballots.
CO releases nearly full by Nov 3
North Carolina will release 80% results immediately when polls close at 7:30pm, so if Biden wins there it's probably over. If Trump wins it can take until Nov 12 to finish counting mailed ballots.
FL, GA, ME, MN, MT, NH, NM, TX are mostly late night Nov 3
AZ, OH, WI are mostly in by Nov 4
Michigan & PA won't be known for a few days after the election.
Iowa & NV count ballots received until Nov 9/10 so unless Biden wins big we won't until very late in
https://projects.fivethirtyeight.com/election-results-timing/