I think my child is autistic - overwhelmed mum

My son is almost 5 years old and I believe that he is autistic. Although i have recognised traits for some time some of his traits were put down to covid and his lack of contact with people during that time. While he does not have a formal diagnosis, over the past year I have began to keep a note of traits as I see them and feel I notice more all the time. 

He is a very happy boy and does not so far seem to display autistic meltdowns. However he starts primary school in August and I am consumed by the want to support him and to try and help him navigate  this to the best of my ability. Although I have very supportive family i am struggling to know who best to speak to for advice for both him and myself and my head is filled with questions. For example I am keen to be as proactive as possible however most family i have spoken too seem to suggest wait and see. I would like some advice on how valuable a formal diagnosis would be at this stage? Should I wait to see if any problems arise when he gets to school and try and deal with them as they occur or should i try and intervene early trying to avoid problems before they occur? I suppose every parent hates the thought of their child struggling and either being unaware or not knowing how best to help them. Some days I just feel very overwhelmed by it all and would just love to talk to someone to help put me on the right track. A friend suggested i find an online forum so here I am.