There are quite a few avocado varieties adapted to Florida. And they bear at different times of the year. One of the earliest bearers is 'Donnie" It ripens in May and June. 'Pollock', 'Russell', 'Brogdin', and 'Simmonds' ripen in July to September. 'Miguel' is a bit later, ripening August to September. 'Booth 7' bears from October to December, and 'Choquette', 'Hall', and 'Lula' ripen November to February.
One of the major disease problems of avocado (in low-lying areas) is avocado root rot. Avoid planting where drainage is poor. Also, foliar fungal diseases such as scab, anthracnose, and powdery mildew are common.
For more details on growing avocados, consult the book All About Citrus and Subtropical Fruits.