
Few minutes to having 4 free builders, after that its gemming to TH8 time. Thankfully, TH8 has almost no offense upgrades, so having high elixir is not really crucial. I have lower elixir because I just started lvl4 loons in lab, and plan to upgrade lab together as soon as I reach TH8.
https://clashguideswithdusk.wordpress.com/2016/11/23/lab-upgrade-and-troop-upgrades-run-concurrently/

First 5 upgrades in TH8 for me are: lab, dark spell factory, DE drill, clan castle and DE storage