If you don't accidentally spend resources that should be used on the PD that turn, 5. If you do, then it depends how much you overspend. So if you don't build anything on that planet, or just leave [cost]/5 resources there each turn, you should be fine.
You should definitely spend all of that steel on a single fleet of arcs and colonise a planet with them. 33/34 arcs in a single fleet would be awesome - instant usable planet 
Population would still be less than 20k.
