In Florida, it is legal for a 16 year old to have consensual sex with someone who is UNDER 24. Under your scenario, it is OK for the 17 year old to have sex with the 23 year old, but once the guy turns 24 he will have to wait to have sex with the girl until she is 18.
THESE COMMENTS ARE NOT LEGAL ADVICE. They are provided for informational purposes only. Actual legal advice can only be provided after consultation by an attorney licensed in your jurisdiction. Answering this question does not create an attorney-client relationship or otherwise require further consultation.