One thing I've been interested in trying, but have not (and I haven't heard of anyone else doing it) is making 2 starters and combining them.
If you need 1800 mL, you could make a 900 mL starter, then when you're confident the consumable sugars are gone, put that in a sterilized container (perhaps that growler) then make another 900 mL starter. You would only need 1/2 of your yeast packet/vial for each starter. It would take longer, and I don't think you'd be ready by this weekend, but I think it should work just fine.
What I did for this brew (I don't have a stirplate) is I used a (roughly) 3000 mL starter. I took a large jug I have, made my starter in that, and then everytime I walked by it in the kitchen, I opened it up, expelled the CO2 in the headspace out of it, let it fill back up with O2, then shook the crap out of it. I probably did this 10-15 times over a 2.5 day time period. I got VERY aggressive fermentation after I pitched. I have not taken FG yet, however.