Sounds good growing! Yeah, the thumb just being there will help, you’re probably using it a little bit without knowing it - just pay attention to the feeling in the top shaft of your dick, especially near the base.
As far as girth gains, it did swell a little during ballooning, but I could never get the girth gains that the guy in the pictures got - they were… dramatic.
You don’t have to get close to ejaculating, but when you do, the effects are most noticeable, so take your time with this - give yourself an hour, and see what happens.
But 1/4 is a great start, keep it up and keep us informed.