Urges and planned exceptions for sugar

If I plan an exception 24 hours (or more) in advance and write it down, for example I decide today that tomorrow afternoon I am going to have a single chai latte (which contains sugar, something I otherwise don’t consume) and then tomorrow when it comes time to have the chai, I find that I actually don’t really want it, what should I do? The obvious answer seems that I should just NOT drink it.

However, I wonder if this is a sneaky way of teaching my brain to make decisions in the moment, rather than ahead of time, and might actually strengthen the urges for sugar rather than weakening them? Like, I wonder if I do this a few times, if my brain will start to think, “I’ll plan to have sugar tomorrow just in case I want it and then I’ll only eat it if I actually crave it in the moment.”