Payment schedule

Last year, when I only had 3 students, I gave the parents an invoice by the 3rd week of the month. Thankfully, when Muriel was here she gave me a different idea of how to collect the money.
There are 68 lessons in the school year. If you are charging $15.00 per lesson that is $1020 per year. She told me this should be devided into 9 equal payments for Sept. to May. The lessons go into June a bit, but there is no payment for that month. This makes 9 equal payments of $113.00 per month. I was nervous about telling the parents this as it was not what I had told them when they first phoned me. I wrote it all up on a sheet of paper to give to the parents in a very professional manner and they all thought it was a great idea.
Just to make collecting even easier I asked for post-dated cheques. All parents except one gave me post-dated cheques. One parents says that she only uses cash so I said ok, as long as she is always a month ahead.
The other idea that my daughter presented was to give a discount if they pay the whole year in advance. I had 3 people utilize this option.