No, I don't check until about a week out, at the most.
If I'm going out west mid-season, I don't check weather until about 3-4 days to it. The weather forecast is simply not reliable more than 4 days out! But the last 2 days, that's when I check weather from multiple sources.
There's actually a valid reason for looking at the weather. Yes, I'll be there no matter what the forecast. But I can choose what to pack and what to leave at home. Most importantly, which ski to take with!
For trips around here or up north, I check a bit more in advance, about a week. Number 1, the weather in California today will likely be the weather here in 4-5 days later. If there's no storm and the current coverage is thin, I might actually cancel the trip! Reason number 2, if there's rain right now and the temperature drops, then it'll take a lot of new snow to cover up all that boiler plate frozen rain. Again, if the forecast leading up to the trip is looking bad, I might change my plan, since there's no plane ticket to lock me down.