One fillup a year is more than enough. I think we used about 300 gallons last year but we also use a wood stove. Wood is free as we cut our own. I just think it's a good idea to go ahead and fill it up now. This time last year we paid about $1.18 a gallon for propane.
Usually we can keep our home warm using only wood until about December, depending on the weather. It's a pain, but hey, it's free. :)
AH! But chopping wood, hauling it inside, what fun! < / just a little sarcasm>