if its only going to be a couple of weeks I wouldnt move them to a bigger pot at only 2.5 inches tall its not likely to be root bound unless you used very small cups disposable cups usually work well if you get decent sized ones up until transplanting outside.
if you mix your soil with organic nutrients like composted manure,maybe some worm castings you shouldnt really need to fertilize atleast up until flowering where you may want to use some form of flowering nutrients.