You can also order DOP online and pick up the pesos at the branch 2 or 3 days later. You can get a mixture of bills or all large or all small. Even got a bunch of 20 pesos bills. Unused bills fresh and clean, unlike the dirty one's in circulation in the D.R.
Saves time and hassle from changing after you arrive. Minimum amount to order is $300. CIBC is the bank that offers this, and no service charge.
The wife ordered some from TD bank no minimum. Took 3 days. Fair rate but the cambio was still better. The advantage was you could order small notes. Stack of fresh 20 peso notes.