Devon, my former layouts i did build in stages/sections. when one was done, i started the next.
i finished them all (save the last, that was interrupted by moving)
for my actual layout i decided to do everything in one run. and…
… i do here a bit, there a bit, place a house over there, build a tunnel right here…
and haven’t run trains for the last six years or more.
so, if your purse is a little short for the total cost, do better, than i.
divide your layout in six or eight sections. build section one plus some provisional track to complete a loop. then add section two plus the needed provisional track, and so on.
that way you will get more satisfaction, quicker play-possibilities and an overall shorter building time.