here is the way i check my tranny fluid,
pop the side plug (not the bottom one or you gonna be doing a tranny oil change)
now when you pop the plug, have a rag directly below the plug just in case of spillover. now if you do get a bit of spillover than immediately you know the level is good. but if you dont, than stick your finger in the hole and you should be able to feel the level, if its just slightly lower than the hole than your still ok, however if its considerably lower like say 4-5cm's than you should just top it up untill you get that spillover.
that was the way i was taught. and it works, its hard to measure actual levels when there is no dipstick however you should know ifyou need a bit more or not when you stick you finger in...
now normally when i check mine it doesnt spillover but if i stick my finger in to check , when i pull out some atf comes out and spills on the ground, usually i know than that im ok.