After any painting to be done. After plumbing of fuel and brakes. After rust repairs and welding is done. Before carpeting. Things like that. Toward the end of a restoration effort. If you plan no other work like that, then it's ready now. It's kind of an opinion driven decision.
Even though someone plans those things, they may wish to drive it with good new wiring now and work around the wiring in a year or two. My comment was toward a planed restoration sequence. Wiring being near the end. It also depends on the era of truck and number of circuits and extras.
It is necessary to have all components in place to see the routing and mock up for cut off lengths of wire. A custom harness or well designed harness may not need that.
I don't know what "phase" your truck is in regarding restoration or what style you plan. Full resto, daily driver, hot rod, restomod, etc.
Ok. Thank you - makes sense.
