does the act allow reschedules? If so, how far in advance do i need to tell them if i need to?
Yes, IIRC, you do not need to notify them; simply don’t show up on your test date. If you want to secure a seat
for a future date now, then you should follow the procedure outlined in the URL below.
The unused test fee remains in your ACT account for up to one year also, so if you want, you can log into your ACT account and request a test date change. The ACT works a little differently from the SAT in that you will need to pay the regular $54.50 registration fee plus a $23 test date change fee, but then ACT will credit your charge card for the original fee.
Here is the link that describes the process.