hey man
you should try to never let your plants completely dry out... even if that means watering infinite times...(jks) but seriously...what you could do is fill those external plastic containers with a bit of water so when the smaller pot dries out it can suck up water from outside and never fully dries out.
with this being said don't overwater
P.S. you might not need to transplant just yet... i would keep them in the smaller pots for a few more days atleast to concentrate the root system in a smaller area
before it gets root bound! efficiency is key
Roots rely upon plant aerial portions for photosynthates and various hormones, while plant aerial portions rely on the roots for water, nutrients, support, and hormones. The delicate balance between roots and shoots can be upset when the root system is too large or too small.
hope this helps