I would strongly advice you to make overloads as soon as you can (this would mean at lvl 92-94. 94 perhaps, since stewing can be annoying). You will make around 4k overloads this way, which should be nearly a lifetime supply. For overloads, you will need need to make 4k of each extreme pot, so start early on those (about as soon as you can make them). As a rough guideline: 4k overloads = 8.8m xp, so start using them as soon as you hit 4.2m xp (lvl 88?). To reach 4.2m xp, make any pot (look up gp/xp at runescape wiki and decide which one, balancing cost and speed) up to lvl 82. At 82, make spec restores and some super antifires (as much as you think you will ever use) untill lvl 88, then start making the extremes for overloads. Using this way you will: a) Get 99 VERY fast. b) End up with useful (untradeable) potions in stead of nothing (let's say you make brews: you sell them at the end so you get nothing, but xp).