Shed roughly a third of what I started at over twelve months before getting pregnant, first on tirz then reta. Used whatever the lowest clinically effective dose was for me, then climbed once that level stopped doing anything on tirz. For reta I bumped monthly, mostly because appetite suppression just wasn't showing up at any level I tried. Went 1, 2, 4, 8, then held at 8 for a while since I didn't want to push to 12. But if reta does suppress your appetite for you, my suggestion is staying at whatever lowest amount actually gets weight moving, and only climb once that stalls. Goal was losing half my starting weight, and the projection had me getting there around the year-and-a-half mark.