When did Sauron leave to join Morgoth?

tolkientatertots:

I’ve been thinking about this and I’m not quite sure when on the timeline Sauron openly rebels and joins Morgoth. Was it before or after Morgoth threw down the two lamps? I know that by the Battle of Powers, that Sauron was at Angband. What I’m curious to know is if Sauron also helped Morgoth throw down the two pillars holding the lamps. Does anyone here happen to know this?