Shanghai Maglev & Metro Pass Question

I am still kind of confused as to how the Maglev & Metro pass works. If I buy a Maglev single trip + metro one-day pass, does that mean I can use the Maglev single trip on the day I arrive to the airport and save the metro one-day pass for later if I don't use it on the same day? Or does the maglev single trip count as my first use, so i have to use the metro one-day pass on the same day? Same with the Maglev Round Trip + metro one-day pass. Do I have to use the Maglev round trip all in one day, in addition to the metro one-day pass all in one day? Or, can I use the maglev round trip for when i arrive at Pudong airport on one day and then a few days later use it to return to the airport to complete my roundtrip?