If I remember correctly it took me a couple of months...i want to say 4-6. Now that was at a slow pace. I am getting back to running after taking a year off to take care of my mom and it is rough. I am no where near what I was before and am just taking my time to get back there. I totally get the whole thing about being discouraged. Keep this in mind....YOU ARE OUT THERE!!! Being out there and just trying is a MAJOR accomplishment.
As for the GU's, they did not bother my stomach at all. Now, I only used them when I ran more than a 15k.