I am assuming you are using an AI and caber and have PCT planned. Saying that run the sust at 500mg as planned. Front load the Deca at 750mg the first week, 500mg the second and shoot 250mg from week three to week seven, this should have the deca active by week three and the dose of 250mg that you want should have peaked and would be active in your system, it will taper off by week 9 leaving you fairly dry by week 10. It is a much better approach IMO and will make PCT a lot smoother also, the last thing you want is to be shut down from Deca.
Run the D-Bol to kick start the cycle for the first 4 weeks and add in a dry compound such as winny at 50mg a day if you can for the last 4 weeks to dry out a bit.
That is how I would run it anyway.