hello
we had to switch my son from a school where he attended K thru 4th grade. the school closed so we had no choice.
What we did initially before attending another school was to have him shadow at another school to see how he liked it and how well he adjusted.
I don't know if you have the luxury or not of doing that in that, sounds like it would be the current school or just one other. in our case, we had three different from which to choose so we asked our son which of the three new schools he liked and he got to choose.
now, since he has begun full-time at the new school it hasn't come without some concerns... mainly that of my son making new friends and fitting in.
at his old school, the kids all knew one another from Kinder so it was easier at that school,. With this new school, he has good days and then not so good days..a good day of course is where he plays at recess and is invited to join in, a bad day for him as he says is when the boys don't want him to play or they are playing some sit down game (things my son does NOT like) also, my son had a set routine with his old buddies which was to play kickball, tag and lots of running around, at this new school, the kids seem more sedentary... That, although not a concern for some, it's a big deal for my son.. on the plus side..his grades are still up, they are very well organized at the new school and while he doesn't always feel that he fits in, he is having more good days... I think it will never compare in his mind to his old school, but it's also important that my son realize change is inevitable...
as for when to leave .. consider this.. you are already into a new school year, maybe let them stay. Also, this will give you a chance towards the END of the year to allow your child to shadow at a new school (before it lets out) this way, both you and the kids can see how it goes.. If it were me, I know I would let me child stay until the end, being as he liked his old school and all.. but thereafter, I would propose the change..