Actually DVC was 15 days in years past. It's now 10 days but it's 10 days from when you sign the contract. If the POS is not available or there are amendments in the interim, it's 10 days from when those are sent to you. The cancellation date is from the date you send it in, not the date they receive it.
The paperwork also indicates that you can FAX your cancellation request to DVC within the 10 days. This is the method we used to cancel on day 8. Within 2 weeks our deposit was refunded in full ( to our D-visa). No questions asked, no calls, no hassles.
edit** It is ten CALENDAR days..not business or working days... (important).