pre carb

I have a gallon done fermenting in a few days. Can I dump it in a couple of growlers and put them in the fridge for a few days uncarbed until I have a co2 set up ready??

I'd leave it on the yeast for that few days, this'll ensure fermentation is complete - this is assuming you've already taken gravity readings a couple of days in a row and confirmed activity has stopped. This'll also give the yeasties time to clean up after themselves. Sitting on the yeast is probably the safest place until it's ready for packaging - less risk of infection, less risk of taking in unwanted oxygen.