I went on the dave yates framebuilding course a couple years ago – and i haven’t built anything since so this is not to be taken as gospel, and i have forgotten stuff.. Also i think having a full jig has an influence, as you can fit stuff and know it’s right before brazing to calculate other things.
The way we did it meant there was only one “vital” length cut where you can’t have a second go at your mitres (toptube to seattube) – pretty everything else had a little leeway or could be adjusted – mainly because one end is going into the bb shell where it can stick through a bit if necessary.
Order was: stick seat tube into BB, stick top tube into headtube, cut the headtube length (the accurate one), mitre the downtube-headtube joint, then into the jig – get the downtube length and cut it (inside the shell again so can be long, just needs more grinding after. Cleaning is a ball ache though, so try not to obviously!).
Chainstays were attached to lugs at some point and were also in the jig for positioning reasons (and no, i can’t remember how all that worked properly at all)
Then stick headtube to downtube, then top tube to seat tube, then downtube to shell, then chainstays to shell
Then fitted and measured seatstays (the basic sticking to the outside of the seat lug design) and put a cap on, then stuck them on, then stuck seatstays-seat lug, then seatstays-dropouts
So yeah – one of the things i got from that is that there’s no reason to make things difficult for yourself, especially if it’s a first time.. however you do it, if there’s a way to avoid making vital cuts and mitres without having the rest of your frame to measure against, take that option!
I know if i was making another frame, there would be a fair bit of adjustment and compensation throughout, depending on how the previous steps had gone. My filing fairly sucked though.