I can usually move naps ±90 minutes with very little negative consequence (±30mins with no consequences). I can skip a nap with coffee at the cost of adding an extra hour of sleep the following night (I had to give up coffee to make normal naps work - trace caffeine doesn't stop me from napping, but does stop the naps from being effective).

Re: "can't nap during the day… on demand" - the adaption period will fix that.