I always save my syns for the evening time, as I know that is my danger zone when I am likely to crave the naughty stuff, by saving my syns it means I can have that treat of a bit of choccie or whatever and still be on plan.
If you have a little notebook or similar, make a note of the times of day you notice you are craving something a bit more substantial, you will probably notice a pattern that it is pretty much the same time of day and can then plan around that to try and keep yourself satisifed for longer, if that makes sense.