As you progress through the first couple of missions that will unlock npcs who will see you between 100-200 crossbow bolts.
When I saw the title of your post I thought it was about the bolts shooting at a 45-90 degree angle(flying straight then instantly going at an angle to hit the target)
then smith them steel ingots and firewood makes 24 at a time get 10 of each theres 240 bolts
Read what he's saying, he's planning to do the vampire questline.
You can't craft bolts when doing the vampire questline, it's dawnguard exclusive.
If you don't care about RP for your character, you can complete the dawnguard questline and become a vampire lord at the end.