If I arrive on a Sunday and get a Navigo Pass at CDG upon arrival, can I just buy the pass and load it on Monday for a week, and also if you look at the price to go from CDG to Paris City Center its 10 euros, and if i hop on and off the metro a few times after I get to Paris, its almost worth paying for a weekly pass just for one day because of the fares... Opinion Please..
If you arrive on Sunday and you need to travel CDG to Paris immediately, plus Metro trips around the city on the same day, perhaps a Navigo Day pass 1-5 zone put onto a Navigo Easy card (17.80€ + 2€ card fee) would be better for that Sunday. (Regular Navigo week pass is not valid for immediate use if you purchase it any time after Thursday midnight. It's validity period will start the following Monday.)
If you will do more than 4 one-way Metro/RER rides within Paris on your 2nd day, you can load on a 2nd Navigo Day pass (1-2 zone at 7.50€) onto your Navigo Easy card for Monday. You can purchase both Day passes (with different zone coverage) at the same time, by specifying the days and zone coverage you need when making the purchase. (Two Day passes loaded is the maximum at the moment.)