I landed at Narita an hour and a half ago and the line for immigration was at least a half hour to 45 mins long. The complication of buying your train ticket to T2 will also add some time since the machines are crowded with people who are using them for the first time so they take longer. I’d say, book the 4:20pm bus and enjoy a rice ball from family mart if you have some extra time to wait. 3:30 will be very difficult to make.