Yes, you can do it- as boss cool-down is 20hrs. Means you got 4 hrs after SS to start it, so you have chance to kill it second time. It is possible as the cool-down for boosted boss is automatically rest after SS starts.
I would recommend to do it until 13:30 CET/CEST time- so you will have 30 min before SS to kill it second time. Always take under consideration that some bosses require additional time to access them or organise team to slain it.