Based on its out-of-control well's latitude (approximate) of 28° 44.20' North and longitude (approximate) of 88° 23.23' West, the current oil slick should reach the following places on these approximate dates with these then current spill sizes in gallons:
Mobile Bay, 5/3/2010, 15.6 million gallons
Gulfport, 5/10/2010, 23.4 million gallons
Tampa Bay, 10/11/2010, 194.8 million gallons
Galveston, 11/23/2010, 242.6 million gallons
This assumes a uniform spread at the current estimated leakage rate. Of course, efforts to plug the leaking well-head and mitigate the existing slick aren't factored herein. Nevertheless, these figures help calibrate the potential scope of the disaster.