Once you've satisfied the requirements for a tier, you have access to all the abilities of that tier. If you don't take everything at once, you can come back and take the stuff you missed by submitting a new form and just noting that you've already hit that tier. You wouldn't be able to get the same rewards twice, though, so no resubmitting for multiple spells.

We'll allow you to submit threads from within the last month in order to bump you up to tier 2. The clause that allows you to submit for tier 3 is good for any act for as long as your character has been a follower.

We've compiled a list of followers and their tiers already, so that won't be necessary!