If conditions were favourable then you could drive to Glacier the same day, or perhaps a better option would be Kalispel making the day slightly more comfortable and being just under an hour from Glacier. There would be no benefit driving, or arriving after dark.
I'm not familiar with I90 but all Interstates are built with gradual curves and gradients so that the biggest of rigs can drive them , so although you might be at high elevation you won't feel as though it's a "mountainous drive" as such.
Glacier will be well and truly in 'winter mode' and as mentioned previously, the only thing that matters is the conditions when you are actually travelling so keep an eye on forecasts prior to leaving. You can get an idea of what visiting Glacier in the winter is like here on the NPS page.