In Florida, if you have a carry conceal permit and purchase a gun at a gun show, you don't have a three day waiting period and in many cases don't have to undergo a background check.
"UNDERSTANDING THE “GUN SHOW LOOPHOLE”
Even though the state places restrictions on retail locations or gun stores, it is still possible for private individuals to sell firearms to other private individuals. If you attend a gun show or purchase a firearm through a friend or acquaintance, you will not have to undergo a background check. (Seven local governments, like Miami-Dade County, do require background checks at gun shows and private gun purchases, but reports show that this is rarely enforced.)This can make things tricky if you are caught with a weapon and have a criminal history or situation that would not allow you to buy a gun in a licensed store."
https://www.davidolsonlaw-firm.com/post/what-prevents-you-from-buying-a-gun-in-florida
"The Florida Constitution also imposes a mandatory three-day waiting period between the retail purchase and delivery of any handgun, with specified exceptions.3 In addition, the Florida Constitution authorizes counties to enact three to five-day waiting periods, excluding weekends and legal holidays, in connection with the sale of any firearm occurring in or on “property to which the public has the right of access” within the county.4 This provision is directed at gun shows and other events open to the public outside of retail firearms establishments. Concealed weapons permit holders are not subject to such waiting periods when purchasing a firearm."
https://giffords.org/lawcenter/state-laws/waiting-periods-in-florida/