This sounds about right. A few thoughts;
1.Make sure the pleats are perfectly even from top to bottom.
2. You could probably stand to add a couple of rows of basting. One between the ones you have and another again half way up to the fell from the top row unless you feel very confident in your ability to keep the pleats straight.
3. For extra crispness in the pleats, steam with the iron for a few seconds then press them with a block letting them cool as they set.