Wow, going straight for the hard stuff.
If you are just beginning a hair loss regimen, I would suggest not starting off with Xandrox 15. Start with something less potent (and less expensive!) like minoxidil 5%, in my opinion. Keep in mind that whatever you start you will have to continue using for the rest of your life. This being the case, it is preferable to start with something that is more affordable and more easily accessible than Xandrox, especially given that you are only in a thinning stage and are not yet bald. minoxidil is easy to get, you can get it at any drug store and now even most grocery stores so you know you can get a hold of it no matter where you travel in life over time.
minoxidil 5 works for most people. If it doesn't, then switch to something more potent and expensive. In my opinion, Xandrox 15 is more of a substance for true baldies to use, people who have truly dying and ossified follicles who need something truly toxic to get those hairs growing. On paper, it is indeed more potent than minoxidil 5, but the extra 10% that it packs might be overkill and not help you any more than a simple 5% dosage would.