In my experience with no training at all, about 15/20 that because i broke like 10 sticks of ram on my first build ever...
Spent like 300$ alone on the ram...
But it all comes with manuals, the mobo manual has almost all the info for the construction, you just need time and be calm, caz i get easily ****ed when my stuff backfires on me.
If you need help putting it together then ask around...