The Universe as we know it took approximately 14.5 billion years to reach 70% De conversion from Gravity decay. Leaving approximately 10.5 billion years until the Universe reaches 100% De conversion from Gravity which will at that point be 0%. (However I estimate that actual habitability will only last another 2.5 - 3 billion years.

I goofed, my estimations are way off (unfortunately). So I am going to toss my thoughts out at this time. My previous statement was assuming that the rate of decay is constant and that the speed of universal expansion is constant neither of which is true... So since there is no way to accurately measure the rate of decay from Gravity to Dark energy (I am sure I can get there eventually), I want to at least work with the known. So here is what I am going to be working on. Taking the figures we have (age - 14.5 billion years, rate of current expansion - 70.8 kilometers a second per MegaParsec give or take 1.6 kilometers pers second per MegaParsec, approximately 70% Dark energy) and going through them and try to figure out what the rate of Gravity decay to Dark energy is in relationship to the size and velocity of the the Universes expansion. I think with all these factors, a fairly accurate solution can be found (and I don't think I am going to like the figure) AND keeping in mind that by definition an Assumption is more than likely innaccurate. But it is a starting point.....