How long does it take for wrinkles to fade after first botox injection?

Dynamic rhytids (the wrinkles that occur when you make facial expressions) will soften within a day or two, and will fully soften by a week.  For the creases that have become imprinted into the skin and become static rhytids (wrinkles that still remain when the face is at rest) it will take time and/or fillers for the creases to soften.  

Botox works by relaxing the muscles that cause wrinkles.
After a few days after your Botox injection, you'll notice the muscles in
the treated areas will not move as much -- this peaks at 2 weeks. From
that point on, the wrinkles in the treated areas will begin to soften and
slowly decrease in appearance over the following weeks and months. The
key to is to have you Botox done regularly, so the muscles remain consistently relaxed as
time passes.

Hi.  Typically, you'll see that the injected area contracts less in about 7-10 days, with good effect by 3 weeks.  Shallow wrinkles caused by animation will go away in this first month or so.  Deep wrinkles, however, may persist for a long time - months.

Any wrinkles from movement will improve with botox injections and stay improved for 3-4 months.  they go back to their normal state after the botox was injected.  Sometimes less, sometimes more depending on the person and their musculature and daily activity (ie amount of expressivity).  Best, Dr. Emer.

The amount of time it takes for "Static" wrinkles (those that are present when your face is a rest) to fade depends on how deep the lines are before you start doing Botox. Everyone is different, and while age does matter, you could be 40 or 45 with a deep wrinkle, or 60 with hardly any wrinkle. The best time to start using Botox is when you see that line with your face at rest. Most patients will need to have Botox done every 3 to 6 months. If you are 40 years old, and the line between your eyebrows is not too deep, it shouldn't take a whole year to see it disappear. Still, remember the line won't go away immediately. I recommend you continue to stay on top of your treatments - when you can totally make the movement again, it is time for the next treatment.