It's a good idea, and for some people it helps them focus on how many syns they're having when as well.
The only thing is that it won't guarantee a weight loss according to slimming world - for that, you have to have between 5-15 a day, every day, not 70 on one day, and 5 for the other 6 days! However, as you'll see from lots of people on here, it works well, but there are a few people who it just doesn't work for!
Fingers crossed your body likes it!