If you just want a relative order without dates, you can try moving your mouse over the little Mario-head profile button and looking at where the link goes. This shows the user's ID, which is assigned based on order.
gamemaster79, your # is 52599.
NintendoIke64 is 53840.
Markio is 53444.
The lower the number, the earlier the join date.
Got it?
Go Moon!