Still feels a long time to wait.
Presuming your ds didn't have his 2 yr check before he was 2, and if he is only 26months now, trust me, the end of August isn't a long wait.
In my authority the longest wait is for the multi-disciplinary assessment after they have seen the Paediatrician for the initial assessment though.
Others may be along to tell you it is different in their authorities, but what would happen here is : You have about a 45min appointment with a Paediatrician. They will watch ds whilst he is there, and might try to engage him, but most of their information is going to come from you. they will generally take a history - from pregnancy, birth and through 'milestones' to present day. They will ask you why you are here / what your concerns are. It is really, really helpful if you think about this beforehand...... write down some notes or some jottings to remind yourself. Think about all different areas of development..... gross motor / fine motor / speech / understanding / desire to communicate / desire to interact / how does he interact - with adult, and then with other dc / eating - what does he eat (or what won't he eat) typically over 3 or 4 days / routines - does he need them, can he cope when things change / transitions - what happens when you need him to stop doing something he is doing / play skills - does he play with anything appropriately or does he just carry things, or mouth things, or throw things, or does he 'play' oddly with thing (eg turn a pushchair upside down and sit and watch the wheels spin, rather than pushing it round with a toy in it) / does he like (or not mind or dislike) different textures.... walking on sand or barefoot on grass....getting mud or paint or foam on hands.... what about the texture of foods he does or doesn't like, is there a pattern / when things go in his mouth, does he chew them or try to eat and swallow them, or lick them or ...? / does he chew his clothes / does he lick fences? / Does he eat chalk and crayons and mud etc ?
I understand that specially trained OTs can help children with sensory processing differences, enormously, but I'm afraid I don't have much experience as my authority hadn't been able to employ them.
I often recommend this book from Falkirk Council. It is written for school children, but much of it translates for Early Years. Full credit to Children with Disabilities Team
Camelon Social Work Office
Falkirk Council
It is a great booklet.
Have a look at P30 - 33 of This from Tower Hamlets authority - they've lifted it from the Autism Education Trust and it is helpful to understand sensory differences.
I hope some of this helps you.
Does he go to Nursery at all ?