There is no single correct age to start. There is only the question of what your face is doing right now and what you want to do about it.
Lines at rest versus lines in movement
The useful distinction is not your age — it is whether the lines you notice are visible only when you move, or whether they have started to remain when your face is relaxed.
Lines that appear only with expression are dynamic. Lines that stay when the face is at rest are static, and they generally take longer and more work to soften.
What preventative treatment actually means
"Preventative" is a commonly used word and a commonly misunderstood one. It does not mean treating a face that has no visible change. It means beginning while lines are still dynamic, so they are less likely to settle into static lines over the following years.
That timing is different for different people. Genetics, sun exposure, skin quality and how expressive you are all move the point at which it becomes relevant.
Starting later is not starting too late
People sometimes assume that if static lines have already formed, the opportunity has passed. It has not — the plan simply changes. Treatment may be combined with skin-focused work, and results build over a longer period rather than appearing after a single appointment.
How to decide
Come in with the concern rather than the treatment. We will assess your muscle movement and skin condition and tell you honestly whether treatment is worth doing now, or whether it makes more sense to wait and focus on something else first.