You level them in parallel. 1 Age wisdom is equivalent to 1 of each of the great people of the same age, so your effective bonus for a given person is the age wisdom level + the individual permenant GP level + the this-run level for that GP (mostly; there are some GP that are not boosted by age wisdom, but you also don't need shards from those GP to buy it). Going from AW x to x + 1 generally costs about as many shards as as taking all the relevant great people from zero to x, or individually from x to x+1. If you get the GP shards mostly evenly, you will generally get AW x, all the relevant GP to x + 1, and then trade in shards to get AW x + 1 and still have enough shards to keep all the GP at level x. Then you ignore age wisdom until all or most of your GP get up to x +2, and repeat.

If you are concentrating on specific types of great people (idle worker science is popular), it is harder to determine when you should start branching out in order to get an age wisdom level, but you do eventually want to do that ... because the cost for most great people goes up as powers of 2, eventually you will reach the point where one more level of the single great person you are concentrating on will take more shards than the next age wisdom level (which gives that bonus plus all the other great people from the same age).

Originally posted by Other:

You level them in parallel. 1 Age wisdom is equivalent to 1 of each of the great people of the same age, so your effective bonus for a given person is the age wisdom level + the individual permenant GP level + the this-run level for that GP (mostly; there are some GP that are not boosted by age wisdom, but you also don't need shards from those GP to buy it). Going from AW x to x + 1 generally costs about as many shards as as taking all the relevant great people from zero to x, or individually from x to x+1. If you get the GP shards mostly evenly, you will generally get AW x, all the relevant GP to x + 1, and then trade in shards to get AW x + 1 and still have enough shards to keep all the GP at level x. Then you ignore age wisdom until all or most of your GP get up to x +2, and repeat.

If you are concentrating on specific types of great people (idle worker science is popular), it is harder to determine when you should start branching out in order to get an age wisdom level, but you do eventually want to do that ... because the cost for most great people goes up as powers of 2, eventually you will reach the point where one more level of the single great person you are concentrating on will take more shards than the next age wisdom level (which gives that bonus plus all the other great people from the same age).

That makes more sense, thanks!

Every new age you get to pick GPs for THIS RUN for the age you unlocked and the prior age(s).

When you rebirth, those GPs move from the This run to Shards for upgrading that GP for a PERMANENT bonus.

Generally speaking the upgrade double in cost each time, to provide there bonus again (additively)
cost = 1,2,4,8,16,32,64,128,256 et cetera
bonus = +1, +2, +3, +4, +5 (Or as dictated by the GP)

The Age of Wisdom requires a GP of every valid GP of that age to upgrade, and then provides the same bonus that those GPs would provide again. Cost is the same as above minus 1.
cost = 1,3,7,15,31
bonus = +1, +2, +3, +4, +5 (Bonus does not upgrade GP, selection GPs, or Civ-specific GPs, Noted with a dash)


You may wish to focus on specific GPs, or round out to gain a bonus to all, generally, I have the following GPs a level higher than others:
Happiness
Idle Workers (Apartment / Condo speed)
Builder Capacity (Upgrade speed for buildings)
Information Age Wonder specific GPs