nappyaddict is there a particular situation you need help or advice on? You may find that if you outlined the issue, we could give you the info you needed, rather than trying to answer with information with no idea if it is relevant, IYSWIM?
To answer your question, DD1's preschool used the funding to increase their staff numbers each session DD1 attended, to release their SENCO to be 1:1 with DD1. As she got slightly older and it became too intense (she is quite a challenge) for one person, they would increase their staffing each session she attended, and rotate her 1:1 duties between 3-4 staff throughout the week.
DD1 has a brain malformation, with global developmental delay and epilepsy. Having said that, she didn't have any diagnosis when she started preschool - nobody was aware she had SN at all, and it was preschool who raise the huge red flag.
DD1 started 6 weeks before summer hols, and by 2 weeks after summer hols had 1:1 at all times. The 1:1 was sanctioned after 1 observation by the INCO and implemented immediately. It actually took around 6 weeks to arrange the funding, but it was all backdated to cover the increased staffing from the day of observation.
She had 1:1 from 2.9, and didn't get her GDD dx until 2.10, epilepsy Dx until 3.1, and Brain malformation dx until 3.4.
She got her statement at 4.1, and started special school at 4.9 in September.