Before my son started school I knew my son was different but I wasn't worried.
My son was a really easy baby. As a newborn he fed really well, slept 20 out of 24 hours and always seemed content when awake. Not much changed for a long time. We got to a stage where he would only go to sleep if I lay down with him but that was ok, wore a bit thin by the time he was 4 1/2 years!
He hit his physical milestones quite early, he was walking at 10 months. I had no concerns about his motor skills.
He didn't start talking until he had just turned 2 and used only single words until he just turned 3 when he put words together to make sentences. It didn't matter that his speech was behind as his understanding was there, I knew he would catch up. He didn't get frustrated with his lack of speech, if he had maybe I would have sought help for him earlier. His pronouciation was interesting(!), I put that down to being a late talker but it didn't matter as at home we all understood him.
Most of all he was happy, I knew deep down he was different, that something wasn't quite right but as he was happy I put it to the back of my mind.
Once he started school, his differences became very obvious, he started to get very frustrated, he suffered from anxiety. The fight started to get him help.
I misss the days before he started school. We were all happy, ingnorant in our little home bubble. My son is still the same amazing person he was before starting school but I do miss the was he was before he started for both his and my sake. Life was so much easier then.