When you are paddling the board nose should be about an inch above the water and you should be able to paddle and feel it glide a little after each stroke, if you don't have a feeling of glide then you are probably too far back, and playing snow plough if the board stops immediately after a stroke you are too far back. On an 8ft board your feet should be on the board!!!
Now important questions, how much do you weigh? You ain't 22 no more, there is a large section in the forum on older

guys and girls returning to surfing, I am also suspecting that if your weigh up near 100kgs then 8ft may be a little short in the flotation stakes.
If you are around 85kgs then the length is great.