Worried about upcoming trip to Glacier due to wild fires

If you are looking for a guarantee - there are none. You could start out today with a perfect forecast for glacier and an hour before you get there a wild fire, volcano ash plume, or any other disaster could strike nullifying your view.
Per your own post you say the fires won’t be out until winter. You might as well cancel now.
Either that or you make your trip and take your chances. No one on here is going to be able to tell you when to go so you won’t be “dissapointed”.