lookingforsunshine just sharing my experiences!
As someone who is adopting a boy (now aged 4, 3 when he came) and not sending him to school until he is nearer 4 and half at the earliest, I would say....
Decide on the match based on the suitability of the child/children not their exact age.
Loosing out on parenting a child because you worry about missing 6 months at home would be a bad idea (IMHO). I know because I felt it too!!! I was all set wanting a child who would have at least a year at home with me before school.
My son will actually end up with almost a year at home but he is doing some preschool sessions to help him adjust and it feels totally right for us both for him to do this, but I have agonised over what was right and I totally get where you are coming from.
So my new ds will not start straight away (my choice) and I have only made this decision (with DH) because it is best for DS.
When we were going through matching I realised missing out on knowing this child because of when he turned 4 would be wrong for us, I did not want to miss out on him because of missing out on a few months at home with him.
Also, yes, you can send kids to school the term after they turn 5 (in England, check where ever you are too). You are not required to send children before they turn five.
Someone from our adoption support team said it can be helpful for our boy (and so maybe all LAC) to join school after other kids have settled. So our boy is the new one settling, after january or after Easter, getting help etc rather than all kids having trouble settling and it may be easier for him to slot into things as they are working (settled) than to join at the beginning. Anyway do get advice regarding your child (if he becomes so) and what is best for him, I am just saying what we choose for our ds.
TBH they are such hard work at times (! All kids, my birth daughter included) when they do do some sessions at school you will probably feel quite relieved. Well I have! We chose a preschool where he could go for as many or few as he wanted (we wanted) so that was our choice, two mornings a week to start.
I do think it is right to do what is best for you and the little ones and this may be different from me so just sharing my experiences!