It varies, but if you go for a 1 bedroom instead of a studio for your time your odds will increase greatly. We usually travel May/June, late Sept-early Dec so I have no clue about January ... but have had trouble adding nights inside of 7 months in Sept, Oct, Dec and have just ended up staying at DLH. Early Nov might not be bad since its shoulder season with no special parties or decorations until shortly before Thanksgiving.
I figured I'd be safe in early June at >7 months as well, just had to change a studio reservation I had from the 1st week of June to the 2nd due to DH's work and found that even though I'm still outside of the 7 month window, studios were gone for the weekend I wanted. One bedrooms were available, but we're trying to do a cheap points weekend so I just wait-listed. Lots of people report wait list success stories on here with VGC. Good luck!