I just stick my finger as far down in the pot as I can in like 4 places, if the soil on your finger is moist and still a little dark and muddy...thats about perfect. I am growing with straight up top soil right now and Im 9 weeks into flower..havent changed soil since the plant was in a cup... its working fine...It's better to water your babies not enough than too much...
well neither is better than the other, i guess....but your plants will tell you they dont have enough water and you can fix it immediately...water too much could mean root rot and it takes days even weeks to get back to normal and dont let the plants sit in the water that ends up in the bottom either...
and if your worried about water getting into all the nooks and crannies, just get a coat hanger and straighten it out and give the soil a couple of stabs or so. the top drying is not a good measurement...I'd say wait till the top dries and then wait 2 daysand soak it real good...that oughta keep you in the clear.