Hola! What area are you thinking of going to live in as the school recommended will depend on that. Enrolement time is now and they start official junior school in the year they are 6 (runs from january to december the school year not like the uk). You can enter a child in at any time of the year
Sxhools run from mid september to mid june with weeks off for xmas, easter, whit week, half term etc but do vary!
If you are coming over in the new year then you will have to take what space they have and it may be a distance from where you are living, so if you are renting you may want to find a living place temporarily and then enrol and move to near the school after she is in.
All the spanish public schools are good, some of the smaller ones will be better for her for obvious reasons.
Once you live here you will need NIE numbers and the empadronamiento - the official certificate from the toen hall toprove where you are living in order to enrol her - the rules cahnge every year but the school will be able to tell you what you need.
I lived in Fuengirola for many years and had my kids in spanish state school there so can help for that area, we are now in Marbella and have experience only of one state and one private school.
Good luck