Definitely fill it with RO the first time. Do you have a RO/DI unit? If so, its no problem to fill it with RO the first time. It will just take a few days.
If you fill it with tap water the first time, the impurities in the tap water will not just 'go away' with the cycling process. These heavy metals and chlorine molecules and other such harmful chemicals stay in the water unti they are removed with water changes or absorbed by your tanks inhabitants. So, if you fill with tap the first time you will have 220 gallons of tainted water that will have to be completely removed via water changes before your water will be as pure as it would be using RO water. Save yourself a headache and just fill with RO/DI the first time around. You'll be glad you did. Good luck!