You receive your bills on the fifth working day of the following month by email. Alternatively, you can also view them in my yallo under "Bills and Usage".
If you have selected the option "Paper bills" in my yallo (charge applicable), you will receive your bills around the middle of the month. If the total amount of your bill is less than CHF 15.00, it will automatically be carried over to the next month. You don't have to do anything for this.