You got an A, you should be fine.
I got an A @ GCSE maths and an A in AS maths.
I did no revision until about March, I did the home works off course. From March till the exam, I did about 2-3 hours of maths revision a day, mainly past papers and Solomon papers.
The good thing with maths, edexcel, is there are so many past papers and Solomon papers and once you finish them, you can just do them again.
By the time the exam came, I had done all the possible types of question and it was just a repeat of exam questions i had already done - expect with different numbers.
Good luck!