I've always thrown my teams together as early as possible, but I'm taking a new approach with my latest project.

I've levelled them to 10 playing as a team, and intend to use my mage to blitz DMines, Stockades and the SM instances. After that, I'm not convinced my mage will be as effective at blitzing simply because she's not at all well geared.

In other words, my new approach is to blitz them to ~level 40, and then bring them together as a team.

So far, it looks great!