Hello from Sacramento: Epicenter of Craft Brewing!

Experience: Three extract brews. Next step: Thinking of moving to partial mash brewing. Too soon?

Nope.  It's easy.  If you have steeped any crystal grains already, you're 80% there.  Next brew, try to start and maintain whatever you're steeping at 155F for 30 minutes. 

I used to put the pot in a warm oven ~170F.  Some people prefer a small cooler. 

Once you can do that, you can mash small quantities of ANY mash-able grain and make virtually any style you want. 

Just assume terrible extraction efficiency like 50% - the partial mash is more about the fresh malt flavor than the SG points you get out of it. 

Thanks, MaltLicker. My last brew was an English Pale Ale in which I steeped 0.5 lbs of Crystal grain in a mesh bag for 20 minutes until the water reached 170 F. Is this step the 80% "there" you're referring to?

Essentially, yes.  But instead of adding grains at 100F and pulling them when the water hits 170F, I mean using BS2 to calculate the strike temps, etc., for you, and doing that procedure.  Partial mash is a mash, so you have some temperature targets based on what you're brewing. 

A large nylon mesh bag should hold 2 or 3 # of grain.  For your EPA you brewed, that might mean 1.5# of Maris Otter, and the rest crystals. 

If you're using a 5-gallon pot, you'd put 3.5 to 4 gallons in the pot, get the water to roughly 160F, and the grains will take that down to ~155F or so.  Then you want to hold that for 20-30 minutes so the MO can fully convert.  That's where a warm oven or a cooler helps keep the temp for you. 

If you were making a Belgian Golden Strong, you might mash at 148F to increase fermentability and improve the dry finish of the beer. 

The fun aspect of partial mash is that using some base grain instantly makes any grain available to you.  The base grain provides the enzymes to convert those grains that are partially dead, enzymatically.  For the EPA, you could try some amber malt, or Bisquit, or anything else appropriate to an EPA. 

Or just  add the grains and heat the mash to 154 and hold for an hour.

If you try this, I guarantee you'll be All grain brewing within six months.  Trust the voice of experience.  Man, If I can add that much flavor out of that little bag of grain, how much more could I get from a full mash?!?!  This is how it works.  I did about one or two partial mash recipes and it didn't take me long before I went all grain.  I'd never go back.  The flavor is SO much better!