What should I do if I don't have turbinado sugar

If you have demerara sugar, you can use that too. Its crystals are smaller than those of turbinado but larger than granulated sugar...

You could use just regular granulated sugar. It won't have the same texture but it won't effect the taste

You could roll them in granulated sugar (or skip rolling them in sugar altogether), you'll just miss out on the extra sparkle and little crunch from the turbinado sugar.