So I just ran the numbers on what I have left in TH8. I just got all walls to purple, so I'm feeling a little behind there. But with 5 builders and hating to see them idle, I got all of the defensive buildings done first. All I have left is one tesla tower to lvl 6 and then my bombs up to lvl 5.
For Gold I need 121,500,000...tesla, bombs and the rest is walls to skulls.
For Elixir I need 20,836,000....50% for maxing all Barracks and 50% for remaining troop upgrades
For DE I need 280,000....150K for troop upgrades and 130K for BK upgrades (from 6 up to 10)
Builder time isn't going to be an issue, but I have 59 days of lab time left. Two more months to earn 121,500,000 gold to get all skull walls. That's averaging over 2,000,000 per day. I get just over 500k from the gold mines per day. That leaves 1.5MM left to earn in raids and wars. That's not much for a single days work, but to do that EVERY day for two months will be more than I should put into it.
Long story short, I think I'm going to pull the trigger on TH9 before hitting all skull walls. Once my last lab upgrade is kicked off, I will probably make the move to TH9.
I pulled the trigger once my core and second level were skulls- still probably have 70 or so at purple, bk at 9, and everything else save for upgraded DE troops. Yeah I coulda/shoulda spent another two weeks grinding DE, but having gotten to that point I was starting to lose interest.