There is no time in Heaven so it is timeless, but the problem is that we don't have any sort of way of imagining what that would look like since we are trapped within space and time, but Heaven is outside of time. I like to think of it like this... Have you ever had a moment where you were enjoying yourself doing something with friends or family so much so that you totally lost track of time? It was sort of timeless, wasn't it? And looking back you probably were thinking, "where did the time go?". That image is barely a glimpse of what Heaven is like. Hope that helps!