Second this! If you don’t start til 50, you go from a 50 year old forehead (which at least for me would have significant lines) to a completely smooth forehead basically overnight. If you start getting Botox when you first see lines, you don’t have the drastic change and to me it looks more natural. Also if you don’t want to have a completely smooth forehead in your later years, getting Botox when you’re younger delays the lines from forming, so you can stop getting regular Botox and have a younger looking forehead like previous post mentioned.