Hey Adam,
I recently flew solo on the 10/10/10 (Lucky day) after 13 hours flying.
I was 16 in August and I wanted to complete it as close to my birthday as
I could however bad weather dragged it on a few months.
It's said that reaching solo flight in under 2hrs is good and anything under 15hrs is very good.
In my opinion it does all depend on the conditions etc because if I didnt fly on the
days which I had bad weather then the time it took me to fly solo would have been
reduced but any flying is good flying so even if it does take you more than 15 hours
to solo you have probably gained alot of experience out of it.
Michael