My DD joined GWC in P1. Prior to that she was in a private nursery in Edinburgh. We dithered about whether to try and get into pre-school at GWC, but there were a couple of factors helped us to decide to keep her where she was - she was very happy at her nursery, and we felt she would cope better with a move a year down the line than at 4 years of age, and pre-school at GWC (this may also be the case at other private school nurseries) only operated during term time and term hours, so we would be stuck with trying to find care for her in the school holidays, and she would have been too young for any holiday clubs. We preferred to have the luxury of private nursery between 8am - 6pm, 50 weeks of the year!
We had heard all sorts of rumours about the intake and how much of that was skewed towards nursery. I still don't know the exact figures (and stand corrected if I'm incorrect), but P1 at GWC is 5 classes of approx 22 kids, so 110 kids altogether. Approx 70 kids will feed in from nursery, which leaves approx 40 spaces for new intake. We took the gamble and only applied for GWC (also looked and liked Heriots and ESMS) and luckily she got in. She had a 20 minute assessment in the Jan, and we heard pretty quickly that she had a place for that year.
The assessment was a chat with a teacher, doing a couple of puzzles and answering some basic questions. Nothing taxing and she wasn't fazed by any of it - it was just going off to play in another room for a bit! Plus they get a report from nusery too.
My DD is now in P3, and we could not be happier with GWC, it's a fantastic school and she's really thrived there. Our DS will be going next year and can't wait. Don't worry about the size of the school - it put me off at first, but p1-p3 are in a mini-school on campus and it has a very family feel to it, you do get the impression that every pupil is valued and treated as an individual.