Contacts/glasses Question-why Do I Have To Get Used To Glasses First?

Hi –
I got glasses recently (I’m 13) cuz I have 20/100 in every eye and slight astigmatism. However, I look like a nerd anyway and my friends told me to get contacts NOW cuz you look so nerdy. SO NERDY like really nerdy. My question-I’m responsible, and I’m willing to take care of contacts for as long as it takes/I won’t break them. I don’t have any headaches with glasses. Why are my parents telling me to wear glasses for a while first?