Welcome back! Good to see another person around my size joining the boards and working the simple fit program. I suspect you will find the the pushups and squats will start to get very easy while the pull-ups remain very hard. This was the case for me, building up your shoulders, arms, back ,and grip to pull up 300 lbs is a large task (I am currently at 293).
I've been working at pull-ups for a while now, even before starting simple fit, and I am very happy with the month+ it took me to get to the point of being able to do 4 pull-ups in a row. Trust me, the gains will come, even at our weight, you just have to keep going at it.
Once you start to drop some weight your body will be accustom to doing 1,2 or how ever many pull-ups at 300 lbs and all the sudden you weight 290 and your able to hit 3 and 4 in a row. At my best I was able to get 15 in a row at 268 lbs, I am hoping to get back to that (and even better!)