IPSEA has all the timescales and legalities, sorry I am hopeless at linking, but that is wonderful news Youare.
Some of our evidence was used in the assessment (ie a recent OT report was just reused, in a different format, and he wasn't seen again by the OT as it had been so recent) Ds2 saw a LA Ed Pysch although we had private report up to date.
The LA failed miserably to sort out SALT assessment, in the end they had to use our private SALT report. So watch out for repeated assurances that something is being organised when it isn't. (in our case bureaucratic mixup he had been discharged from SALT list without ever being seen, which is why the assessment never came through)
The Case officer can be misleadingly glib when she has no idea what is going on. Although our second one who replaced first was much better.
The most difficult bit was filling in the long sections in ALL ABOUT ME etc. [They should send you a long letter and forms to fill in] I asked for help with this from the Parent Partnership, they were very helpful to giving me the right way to phrase things and what to include. I used lots of very simple examples, like I want him to be able to go the park by himself, arrange a cinema visit with friends by himself, travel on public transport by himself safely]
Essentially they should send you a letter telling you they are going to assess, with a named case officer.
Ipsea say on their pdf 10 weeks from agreeing to assess until they decide on EHCP or not. We received a very badly drafted plan by week 8, although that still did not mean they had decided to issue EHCP, just a PLAN.
So IPSEA has the info!