Last year, we refreshed the page at 5.01pm and the results were available to read. However, the email itself didn't arrive until 7.30pm. So the moral of the story is don't wait for the email, just log directly onto the system just after 5pm.
yes, emails seem to be released in batches to try and stagger people logging on. You will find the info is only uploaded as the Council staff finish work so they don't have to take calls on 1st. You will be lucky if you can get them on phone on 2nd.
Sometimes the info is sent to your existing primary school earlier, they will probably know Monday 29th (but wont tell you they already know).
Remember the online result will only tell you what school you got into, you then have to wait for your postman to deliver the additional info such as test results.
If you are unlucky, you also generally have to wait about another 3 or 4 weeks to find out your position on waiting lists as they only seem to release this once the first acceptances / rejections come in (which is supposed to be done within 2 weeks, but some parents are slow). If you get school number 1 on your list, I think it automatically accepts the offer.
What I'm trying to say is don't count days to 1st March, (which is presumably why this thread was opened) or arrange a celebration evening on Tuesday 1st in advance. A fair chunk of applicants wont have any certainty that day, and could be many more weeks of waiting as clearing takes place. Remember there are thousands of places offered to people initially, who subsequently decline the place as they go to a private school outside the main offer system.