Yes, you could store the points and give your PC the 1-2 point evolution, and then change them out when you gain a level, just as you can change the delegation of the other evolution pool points.
I'm not too good with formatting so someone else is welcome to reformat this...
Aspect
At 10th level, a summoner can divert up to 2 points from his eidolon’s evolution pool to add evolutions to himself. ... The summoner can change the evolutions he receives from these points any time he can change the eidolon’s evolutions.
Evolution Pool
(from Eidolon abilities)
... Whenever the summoner gains a level, the number in this pool increases and the summoner can spend these points to change the abilities of the eidolon. These choices are not set. The summoner can change them whenever he gains a level.
The way I've read those is that every time the summoner gains a level in Summoner, he/she effectively resets the evolutions, gains the full pool of evolution points, then spends them as desired. With the Aspect ability, you are diverting points from that pool at any point you could change the eidolon's evolutions.
Thus, when you gain a level and want to store points, you divert the two from the evolution pool. The next time you gain a level, you choose whether you'd like to divert 0, 1, or 2 points with that ability again.