Nothing wrong with going to full synthetic early on. Lots of cars (mostly German) come from the factory with full synthetic. There's really no downside to synthetic, it just resists breakdown a little better so you can often go longer between oil change intervals. Well I guess the one downside is price. Your car isn't going to run any better on synthetic, you just may feel better about it.
Synthetic oil just uses synthetic base oil instead of petroleum based, then pretty much the same additives are used. Advantage of synthetic base is that they can design it the way they want vs. petroleum based where you are somewhat limited in how you refine it. But a lot of synthetic oils still use a petroleum base that has been highly refined, broken apart and put back together. It's technically not synthetic, but its properties are and here in the US, it can be labeled synthetic. I believe in Europe it cannot be called that.