Of course there are loads of summer borns who have no difficulties at school and are high fliers etc, but statistically, summer borns as a group do face some disadvantages, which are charted right through to GCSEs....this is based on the whole population, not individuals who will buck the general trend in both summer and autumn born.
I'd say, we are near to the time you'd have to wait until,mot get an Autumn born. Therefore I'd wait, in the knowledge that I might get lucky as it were and become pregnant immediately, but also be fine with the fact it might not work out and their might be a Christmas, or Soring or summer the following year baby, and that whenever the baby finally arrives will be just fine.
It's okay to have a top preference and to plan towards that, as long as you're fine with things not quite working to the timings you'd like in an ideal world. And it's not a criticism or judgement on anyone who has or will have a summer born. Some people seem to take this kind of thread as a personal criticism of them or their child. It really isn't.
Lots of people hope for an Autumn born. Teachers often do, partly as they can get paid over the summer,not hen start their maternity leave and return in time for July and another paid summer holiday....but mostly because they see the more macro effects across many children (rather than individuals) of being older or younger in the year,me specially earlier on. However, as said upthread, some might aim to avoid a winter baby because of the cold and health issues, or some might like a summer baby for enjoying being outside or avoiding being pregnant through the hottest part.
Nothing wrong with having a bit of a plan and aiming for it, as long as you know that babies don't come to order and are happy with whenever they eventually arrive.