The general rule is to wait about 3 months after cancelling, before reapplying for an Amex card. That said I've reapplied for the Biz Gold Rewards card within a week after cancelling without issues. However, I may have been lucky, as there were others in the past (look in the older 2013/2014 Amex Canada threads) who have reported that a newly cancelled account was re-opened when applying too soon, such as within a month after cancelling.