@Crochetmadmama
It's so hard to know if you are making the right decision isn't it.
As @SavetheNHS has said, we can wait until they are older/old enough to decide.
However, perhaps they will be grateful we made the decision for them and it is done and out of the way while they are younger.
We see different orthoptists as we go every 6 weeks and one is quite relaxed and is giving me the impression they think we should wait, whilst another was speaking from a mental health/self confidence perspective and seemed to gently suggest we go ahead when the time comes.
My gut feeling is to go ahead once we can whilst she is still quite little and may forget most of it... however it is worrying knowing that it might not work/last.
My little girl is already self conscious and cries saying 'stupid patch, nobody wears this except me' every morning. She isn't actually aware of the squint yet but once she is, I know she will be very self conscious.
On the other hand, she is petrified of doctors, needles, most things medical! So the surgery will be very frightening for her.
Sorry for the ramble. I know you must have gone through all of this - or similar - in your head to have reached your decision for Thursday. You will be doing what you feel is right for your daughter. Hopefully you have had the chance to ask all the questions you wanted and they have been honest in what to expect.
Keep thinking positive - they do this surgery so regularly and if they feel it is right for your daughter, hopefully you feel you can put your trust in them and it will be an excellent outcome.