I restarted today, however next saturday I'm going out for a meal for my birthday. I was thinking of saving up my syns to use then. Would going for 7 days using little or no syns mess up my weight loss when I go back to normal the following week?
Where are you thinking of going for your birthday meal? It'll help to plan ahead re what you might choose to eat / drink so you can decide if best to be green / original / ee, and how many syns to put aside.
Try to leave enough so that the rest of the week isn't too horrible!
If you're going to have a flexi syn day you need to decide beforehand how many syns you are going to allow yourself. That way you still stay in control. Also by having a flexi syn day you need to be aware you may gain or STS at next WI, will you be happy with this?
Don't forget you can have up to 105 syns per week, I really think you'll struggle to have that many on your birthday. Perhaps for this week you could use your syns on a weekly basis that way you still have a nice time & stay in control and possibly over the week within your syn allowance.