We did this at a shower I went to last year and I thought I would pass it along to you ladies in case you are looking for some alternatives...
The host had a TON of cards and had everyone write something in them, on the envelope it said "open when you are [blank] years old" and there was an envelope for like 35 years maybe more since there was a ton of people there.
I thought it was pretty neat that the people who were at the shower got to write advice to the baby to be for their birthday on whatever year it was they got.
So there you go, take it or leave it