@apoli what i do is, like nynaevelan, if i have at least 80 orbs of the legend/epic, i summon them now. If not, just hatch and instantly gem them at the start/end of heroic. Pretty fair price to hatch, about 12 gems or less per hatch.
If you catch the quests at the very beginning, you can do them all without using gems to speed it up plus some wiggle room if you miss an hour here and there a few times.
Quest 1 for 120 orbs requires all dragons to be level 30 at the end, and level 30 at the beginning of quest 2.
Quest 2 for 200 orbs gets tricky in the middle. Although you only need level 40 for the legend and epic, you need the heroic to be empowered to 1 star (so if u get early access to heroic orbs during the race, then you can empower it before race ends..... but that’s not likely because the orbs are deep in the race). End of wuest 2 requires level 45 heroic, level 40 legendary/epic.
What i usually do is go as far as i can with quest 2 with a level 40 heroic without empowering to grab about 120-160 extra legendary orbs. If you want to get the 200 heroic orbs, then you’ll have to use gems to speed up quest 1 (a lot of gems) to use the 120 heroic orbs to empower then use more gems to speed that up(about 60 gems). To me( just my own personal preference), I don’t like to use that many gems to speed up quest 1. Too expensive for my blood. So i just do quest 1and 2 simultaneously unless i finished the race and have the heroic orbs to empower early.