When can they start being spoiled?

Lauren. • 28 years old. Happily married since 6/21/14. Loving being a mommy to my 2 amazing daughters!
So I know they say you can't spoil an infant, and I totally agree. I feed on demand (and will continue that...when you're hungry, you're hungry...nothing anyone can do about that), but I also comfort if she cries(I let her whimper a bit before I tend...but I never let her fully cry at this point),and hold her during one of her daily naps (mommy loves her morning cuddles...)However, at a certain point they will start forming habits based on what we do...what age, approximately, do I have to start worrying about spoiling her/forming bad habits?