AOS, name change and new passport

[RedSheep 0]

Hello everyone,

after searching the Internet for several hours without finding answers, here comes my story (I simply can't be the only one with this issue...):

I'm a German citizen.
I am going to marry my fiance using a K1 visa and will take his surname.
So at some point I obviously have to get a new passport with my new last name.

The question I have is: WHEN do I do that???

1. File for AOS - 2. get green card - 3. apply for new passport

OR

1. File for AOS - 2. apply for new passport (I will get to keep my old one containing the K1. The embassy just marks it as unvalid) - 3. get green card

The second option would be a little more handy for me as my current passport will definitely expire before I get the green card. So for the first option I would have to get a new passport now (so it doesn't expire during the AOS process) and another new one when I change my name *sigh*.

Does anyone have experience and/or recommendations??
All that I found so far are the how-to's on changing the name with the Social Security Card. But for some reason there was no information on passports.

Thanks in advance =)