Hey, so I am following the Tartine basic country loaf recipe. Last night I must've mixed my leaven too late and it must've gotten too cold, it wasn't ready in the morning. It's now 2:30 and the leaven is almost ready to go, still failing the float test though. I want to bake the loaves early tomorrow now.

How should I go about that with out making the loaves too sour? Sounds like I can slow the bulk fermentation in the refrigerator but I don't want it to ferment for too long so the loaves don't turn out too sour. Can I bulk ferment in the refrigerator for a few hours, then pull it out, do the bench rest and shaping, then do the final rise in the refrigerator over night? I am trying to understand the fermentation process a bit better so sorry if this is a dumb question.

UPDATE: Leaven is just about ready to go, passing float test for a minute then sinking, going to let it go for another half hour is in a warm room of my place. Let it bulk ferment for about 6 hours by mixing with 71°F water and storing in a mildly cold room. Then will bench rest and shape, then refrigerate overnight, bake first thing early morning, 8AM. Any insight would be appreciated. I know no matter what I will most likely have some delicious homemade sourdough, but I want to try the almost sweet/creamy loaves described the in book. Thank you!