Like I said, you should be able to feel the eggs at least a week prior to them being laid, so probably about 3 weeks in. Once they are shelled and descend farther down in the abdomen (below the ribcage) to prepare for being laid is when you can feel them. Right before they are laid the eggs will descend even further, lined up one on top of the other in the pelvis and you might think they have already been laid because you don't feel them in the gecko's sides anymore if you don't realize what is happening.

Laying every 25 days is a little fast, but each female varies a little. Every 28 days has been a minimum for my girls, with 30-35 days or so being a more normal average (but I don't check lay boxes every single night, so the average isn't exact). They can also slow down toward the end of the season and/or when the temps start to drop.