Is there a minimum time limit if a marriage does not take place before I can retrieve the engagement ring or sue?

No. More facts need to be known to address the issue you raise.

If you do not marry, you can have the ring back. This is state-specific so I defer to FL attorneys for more specific advice.

Florida, along with a majority of other jurisdictions, consider the ring to be a conditional gift–meaning the gift can be revoked if the recipient does not fulfill the conditions attached to the gift. Of course, the condition being that the receiving spouse marries the spouse gifting them the ring. Ask for the ring back.