f4n70m is right, those "gauges" are not accurate. You need to get digital thermometers with probes and a digital hygrometer. The gauges can be off by 10* in either direction. The accurite weather station measures your hot spot temp, ambient air temp, and humidity. It can be found at walmart, home depot, or lowes for about $12. I highly recommend you purchase one.

If you live in a hot climate then ditch the heat lamp. The heat lamp will lower your humidity significantly. Just use the UTH regulated with a reptile thermostat to prevent burns.

How often to feed really depends on what size prey is being offered. If one chooses to offer the smaller size, a feeding schedule of every seven days works well. Slightly larger prey items can be fed every ten days. Excessively large prey items will cause the ball python to refuse food on its own for an extended and unpredictable length of time.

Ball pythons seem to do well on a regular feeding schedule. Feeding every seven days on the same day of the week is a good way for the keeper to track the feeding schedule as well as being a routine the snake can become accustomed to. However, there is no one right way to go about it.
Where does this say to feed every 3 weeks? You should be feeding your snake every 5-7 days. If you only feed it once every 3 weeks as a baby, you will starve it.

You will know when he is comfortable when he sleeps in his hides all day and comes out for an hour or two at night to look around. If he is wandering around excessively and climbing the sides of the tank then he is still stressed.