Originally Posted by uds0

As soon as you make the 3k of purchases, the 46k points ($460) become instantly available and can be applied to any travel expense immediately within that 3k of purchases, or any other travel purchases within the last 120 days.

The $500 expense in month 2 also gens an additional $10 of credit for travel expense reimbursement.

Points can only be applied in 2,500 increments if less than purchase amount being reimbursed, else they can be applied as exact amount of purchase.