Step 10:
Ferment...i split this 5 gallon batch into two 3 gallon fermenters and topped off with tap water. You may not be able to use your tap water to top off...you can either boil and cool some h20 or use bottled water if you'd like. I also used two different yeasts (notty and windsor) and eventually blended them back together into one keg.
As for target gravity, i usually shoot for the middle of the style at 65% efficiency. i've experienced as low as 60%, but it's usually in the 65-70 range. as this is meant to be an enjoyable brew day, i don't take a sample until the beer is finished, poured and topped off.
EDIT: Since using the 10 minute sparge, my efficiency has been at a steady 70% efficiency for the last 4 batches.
I hope this helps inspire some people to make the jump to partial mashing from extract! all you really need is the bag in addition to some regular equipment to see how easy it is. once i started doing this, there was no turning back. i regularly make partial mash and all-grain batches nearly 3 times a week now.
let me know if you have any questions on this process or if you need any easy partial mash recipes. some of my favorites are hefeweizens, dunkelweizens and cream ales, as well as the irish rye stout in my drop down.
Take care and keep brewing!