Hi most playschools can now take children from 2yrs 6 months due to a change in the Childcare regulations. The only thing is with the huge demand for school places a lot of children aren't getting into school until they are nearly 5 rather than at just 4 (particularly for May, June, July and August birthdays). This means your child could easily be at playschool for 2 or more years if they start too early. Not in itself a problem but something to consider when you are thinking about what age they should start.
I'm not planning to put Eoin into playschool until he's 3 but right now I have have him at The Litte People's Academy 3 afternoons a week and may just continue with the Montessori there as the surroundings are familiar and so are the people.