X2.
Clean the oil off the inside of the dipstick tube hole and tube then give it a coating of RTV on the inside of the hole.
It does little if any good to put it on the tube and oring.
When you put it back in try not to move it around at all, but just slide it into place and get the bolt in it and that should do it.
Dry time is not needed, but if it makes you feel better to wait an hour go for it. :D
PS. it helps to start the car for 10 seconds or so to get the fluid level down before you open anything like dip stick tube and speedo gears.