What I did and would do again:
1/ Awaken Ramagos ASAP. Doesn't have to be Ramagos, any farmer will do, preferably nat 3 or less. Keep farming scenario with it.
2/ Work on Shannon, Bernard, Kona, Bella as you get them. Probably Colleen now as well (she was bad back when I started).
3/ 6* the farmer and Shannon, Bernard, Kona, Colleen, Bella, in any order that you think is good.
4/ Hit player level 40. I did this in 20 days because I did scenario (gives lots of player XP) except to awaken things. Ramagos can farm fine with scenario runes. I think you only need level 35 to buy good runes though. I actually got Bella after hitting 40 (people are more likely to add a level 40).
5/ You should have a lot of mana by now. Buy 6* 2/4/6 runes from the shop (5* if SPD). Arm your GB10 team up.
6/ Go straight to GB10 with Kona/Bella/Shannon/Bernard+X. X can be your farmer. My Ramagos got 40k HP at this point and could solo the boss. Darion/Michelle/extra Kona are also very solid I think. This took longer than I thought (3 months) because I was stupid and used Wind Sylphid (I know she worked form some people but not for me, devilmonning her is the decision that haunts me the most in this game).
7/ Farm GB10 a lot. I got into DB10 too soon which was a mistake in retrospect. I would say farm GB10 wil you have a 250 SPD monster, but whatever you're comfortable with/