well done!!! fab that you have spoken to someone at the lea who is speaking sense.
that's why i said speak to ipsea tbh - they will be able to advise you if the pre-school is going against dda advice.
tbh, it sounds as though things will start improving this week once the sta outreach and the ed psych complete their assessments.
once you have received their reports, you need to make an appointment with the pre-school manager/ senco (usually the same person ) and go through how they are going to translate the advice into the iep.
(do you have copies of the iep they currently have running for him?)
google 'smart targets' for ieps, there's tons of stuff on the web.
sometimes educational settings need to know that you know what you are doing, and that you understand what they should be doing, too... and that you will pull them up on it if they don't.
relationships with education settings can be a bit fraught tbh, but i always always always make sure that in my dealings as a parent i bow to their superior educational professional status and flatter them into helping.
(in a 'we are both working for the best for little timmy and i'm finding it so hard, i wonder if you take the time to explain iep target setting to me' etc etc)
at his age the ieps should be rewritten every term, and you should be involved in the process - you should be reviewing the targets and signing to say you have seen them, and at the ends of term you should be invited back to review the achievements and help to target-set for next term.
targets can be social as well as academic (uaually are in this type of situation) but quite clearly state how they are going to help ds meet the targets and what support they will give.
it will be ok - it just takes time to learn the system and ensure it is working to support ds. 
but def keep the name and number of the friendly face at the lea.