Coffee in a porter recipe help

Hey brewers, I am thinking of making a coffee porter today but I need some advice on how to add coffee to this recipe. How much coffee should I add and when should I add it? Here is the recipe to help:

Recipe Specifications
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Batch Size: 5.00 gal
Boil Size: 6.84 gal
Estimated OG: 1.078 SG
Estimated Color: 60.0 SRM
Estimated IBU: 39.9 IBU
Brewhouse Efficiency: 70.00 %
Boil Time: 90 Minutes

Ingredients:
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Amount Item Type % or IBU
11.00 lb Pale Malt (2 Row) US (2.0 SRM) Grain 69.40 %
1.75 lb Special B Malt (180.0 SRM) Grain 11.04 %
1.10 lb Roasted Barley (300.0 SRM) Grain 6.94 %
0.50 lb Black (Patent) Malt (500.0 SRM) Grain 3.15 %
0.50 lb Chocolate Malt (350.0 SRM) Grain 3.15 %
1.00 oz Nugget [13.00 %] (60 min) Hops 39.9 IBU
1.00 oz Chinook [13.00 %] (0 min) Hops -
1.00 items Whirlfloc Tablet (Boil 15.0 min) Misc
1.00 lb Milk Sugar (Lactose) (0.0 SRM) Sugar 6.31 %
1 Pkgs American Ale (Wyeast Labs #1056) [Starter Yeast-Ale

I french pressed Starbuck's Sumatra to get about 16oz of coffee. I put that in a bowl in the fridge overnight. Spooned off the oil on top the next morning and it went in the boil at 10min remaning.

Awesome Coffee aroma and flavor in my Breakfast porter. Recipe is on here somewhere.