Lager yeast starter question

I made a 3 gallon (huge, I know) starter on Friday night, and I am planning on pitching Sunday night (48 hrs).

I am planning on cold crashing the starter and decanting the beer before pitching.

2 questions:

1) At what temperature should I cold crash? Is 50F too warm? Since 50F is fermentation temp for a lager, will it really floc out? If I must go colder, can I just submerge in ice bath?

2) What is the minimum amount of time I should wait before decanting and pitching?

Thanks

I would just throw it in the fridge, and decant right before pitching. ~38F or something...whatever your refrigerator is at.

So today is brewday. My starter has been going for 38hrs. Yesterday there was some activity, and this morning was high krausen.

Seems I have 2 options at this point, and I am split as to which one to pursue:

1) Crash cool now (over 10hrs) so I can decant and pitch yeast when I'm done brewing this evening

or

2) Let my starter continue cranking all day, crash cool tonight, and pitch tomorrow morning (My wort will be sitting idle in the fridge overnight)


Important things to note:
-Starter size = 3 gallons
-My starter began with only about 1/2 a vial of white labs southern german lager yeast (really 3 vials of old yeast estimated at 15% viability)
-It's been on a stirplate
-Starter has been going for 38 hrs


I've checked out some yeast growth charts, and they indicate that most growth should be done by 38 hrs. However, I am a little hesitant to apply this metric to my starter because in my case:
1) it took a while to see the first signs real activity
2) this morning was the first sign of vigorous activity (high krausen)
3) my starter size was huge (3 gal), and began with 1/2 vial yeast

I'll take door number two, Bob.

Lucky for you, 838 floccs out pretty well. I really dig that yeast!

I have my kegerator set to 50F which is the temp I'll be fermenting at.

You think this is cold enough to floc out the yeast?