If I'm not actively trying new things, I try to keep anywhere between 2 and 4 weeks worth of juice on hand. However that's partly a buffer to allow for longer shipping times to New Zealand and no B&M vape stores close to where I live.
Juices are a little like music, or fashion - constant evolution. You'll probably find your tastes develop and change as you go along, and it becomes a journey looking for new companies, trying different things, checking out products that get heaps of hype. I think most people tend to try a lot, find a few they like, and a few more they don't. From there, many people branch out into DIY. I initially started out with tobacco flavors (mainly Halo), then went through a period of really sweet fruit/candy juices (mainly Fuzion). After a while I picked up the taste for creams and deserts (mainly Suicide Bunny), and now I'm starting to get a taste for custards after trying a few from The Standard.