What's the youngest age you think one should get botox and/or fillers?

Been seeing a lot of young influencers (as young as 20-21 years old) getting jawtox, chin fillers, and soo many beauty treatments that involve putting things into their bodies. I'm not near that age yet but I'm interested in beauty treatments and would someday like to get them. What's the right age to start getting botox and/or fillers? What are the pros and cons when you get them as early as 20/21 years old?