3D ultrasound at 17w 5d is that too early?

Chalyse
My name is Chalyse and I have a DD from a previous relationship where I wasn't ready to be a parent and didn't have the finances to do all the things possible to do with my pregnancy. This is my second but my husband first and he wants to wait  until 20 weeks scan. Now money is not the issue he is saying I am just impatient(which I could be)   but I would just want to experience things I wasn't able to with the first one. Am I being selfish?