There's no one "right" approach to smoothing out wrinkles, there's no "right" age to get started with injectables. However, depending on the decade when you decide to get your first treatment, your experience might vary a bit
The question of "when," really depends on the stage of your wrinkles, and how deeply they've etched into your face. The progression of those wrinkles does correlate, to some extent, with how old you are, because of the changes your skin undergoes as you get older. Your skin's natural production of collagen and elastin slows down around the time you hit 30, and factors like sun exposure and lifestyle habits like smoking, your diet, and stress levels can all play a role.
In your 20’s
In your 20s, Botox is used largely for preventative purposes. At this point, wrinkles are considered "stage one," which means that they show up when you make an angry face or furrow your brow and stick around for only a brief amount of time before disappearing completely.
If the lines aren't there, you don't need Botox, but if lines show up when you make a face and show up for a few seconds or minutes afterwards, that's where you’re going to start developing permanent creases in the skin architecture, so you want to start doing Botox at that point to prevent those lines from laying down.
In your 30s
This is the time when the natural production of collagen and elastin starts to slow down, and their dynamic wrinkles start to progress toward static or "stage two" lines. While the stage one dynamic wrinkles only appear when your face is moving, these stage two static wrinkles are always around, even when your face is at rest. The amount of Botox you get tends to (coincidentally) correspond with your age.
It's worth noting that the amount of Botox you get also depends on the strength of the muscle in a given area. Someone may get more units if they have a stronger brow and still have a subtle effect. The number of units you get helps to dictate how long you'll see the injectable's effects.
In your 40s
If a wrinkle has set firmly into your skin, to the point where makeup starts to get caught in it, it is considered "stage three." At this point Botox is used more as a treatment than as a prevention and can help to soften lines that are already there but can't get rid of them entirely. For someone who has stage three lines, when the Botox starts wearing off, you'll start seeing the lines sooner even though the Botox is still there. It becomes more obvious because the lines are deeper, so when they come back at 50 percent, it's more visible than they would be if they weren't as deep to begin with.
In your 50s and beyond
When your wrinkles progress to "stage four," which is characterized by deeply etched lines, there is only so much Botox can do. Botox can soften the muscle movement, so it can keep those lines from getting deeper, but once it is deeply etched in it’s not really going to reverse the lines that have already formed to any significant extent. If you want to truly get rid of the lines, you will need to supplement Botox with a secondary treatment, like -