Yeah I have been wondering about that too.....since Jack had to wait till his clothes to drued then how long was it till he went up the mountain to meet Ennis when he was all dressed in dry clothes again. I can't imagine that the clothes dried too fast on the chilly, cloudy mountain, so maybe it had to be a few days later?
Actually, seriously, you do touch on something here that others of us have wondered and speculated about: the passage of time between their first time in the tent, the "I'm not queer" conversation, and the second time that we see them in the tent.
It's tempting to assume the second tent scene took place on the evening of the day of the "I'm not queer" conversation--and maybe we're supposed to assume those two events took place on the same day--but when they have that conversation, it looks like a very dreary and cold and probably damp afternoon--they both have their gloves on, and Jack has that fleece-lined jacket of his buttoned up to his chin.
But the night of the second tent scene, it looks to me like the weather is downright warm. Jack is shirtless in the tent, and Ennis is out by the fire without his coat. It can't just be that the fire is warm enough; they have a fire the night of the first tent scene, but before they try to sleep, they're all bundled up. Ennis has his coat on, and Jack's wearing his jacket even in the bedroll.
Maybe the weather just changes awful quick up there on Brokeback.