On the History column (in the Maps and Historoy link) at the bottom is census 
for 1783 Spanish  for east Florida.  It is the first I have found and even 
putting several key words in a search egine did not bring any hits that 
qualified for Spanish census ut they had eveything else.  Beej

 Maps & History 
http://hometown.aol.com/gregwain5/maphist.htm

Som of these census have the word slaves beside severa says slave schedule
 Census Online - FL 
http://www.census-online.com/links/FL.html

US Genealogy Map Project --- Land Transfer Eventss to Statehood 1845
 USGENMAP-Florida 
http://www.incolor.com/leonard/usfl.htm