PLEASE RESPOND

I’m looking into starting a Roth IRA I am 20 years old. But I have 2 question. 1. Am I too old? I keep seeing posts of people who started at 18. 2. My most important question is can I invest money I’ve saved my entire life payed by cash working with my parents who only pay me in cash so it’s not income that’s been taxed from what I know.