The best advice I got in the beginning of my parenting adventure ... whatever you think they can do/understand take it times ten. Another good one... follow their lead. If they are asking, I don't think it is pushing. At 3 when we left naps for quiet time, I always left my dd a "project" to work on in her room. Sometimes she made invitations out to friends, did a specific craft, etc. I didn't look at it as enrichment. It just made her happy (and kept quiet time alive for me ;-).