Quick-acting Botox? how come my botox has taken affect on my forehead first after only one day?

When Dysport performed their clinical studies, the data was captured from the first day after the injection. Hence, Dysport is able to make a claim (based on scientific information) that it can work as early as 24 hours post injection. Allergan (Botox) did not capture the data as early in their studies. However, Botox can work as quickly as 24 hours or take as long as 10 days. There is a large variability in how patients respond, with the average time of onset at 72 hours.

Some patients do find that their Botox starts to work within a day, others a few days, and others more than a week. Dysport may have a quicker action of onset, although this still needs to be determined.

It would be curious to find out if you were injected with Botox or Dysport. Dysport tends to have a more rapid onset of action, most patients seeing its effect within 24 to 72 hours. However, some patients injected with Botox will see its effect more more quickly, especially if the effect of their last injection has not fully worn off.

Although Botox can work after one day, especially if the muscles have not fully recovered, it's quite uncommon. Dysport does work in 24 - 36 hours. I'd be curious if Dysport was used instead. I prefer it to Botox for just that reason.

Most patients receiving Botox (botulinum toxin) injections begin to notice effects in 3-5 days, and the maximal effect may take up to 2 weeks to be fully appreciated. Some patients may have a quicker response, just as some patients have extended results (6-8 months over the usual 4-5months).
Another conisderation is that you were injected with Dysport, another very similar but unique, form of botulinum. Dysport tends to have a more rapid onset, but I find the effects do not last as long as Botox.