the main element to consider is always your motivation for the change. Normally, you want to move to a company better positioned to your goals, thus you should do due diligence in advance to ensure the target company fits that (eg faster career, higher position, better work-life balance, better culture...)
The best time to switch depends on your goals - people switch at all levels of the hierarchy, although usually it happens at Manager/Principal level. And yes, I would say it is pretty common.
You can find some other general tips on that for MBB lateral hire, mainly true as well for 2nd-3rd tiers, at the following link: