We have a two ticket flight coming up, JAL arriving from the US at around 4pm in Business and then a separate ticket on Singapore also in Business departing around 8:30pm. I've always been Oneworld to Oneworld so never swapped terminals, looks like we'll arrive in T2 and transfer to T1S. My wife likes to stay put in a single lounge, I like to lounge hop. When we go through transit security is it going to be possible to visit the Oneworld lounges in T2 then do the bus transfer over to T1 and settle in the ANA/United lounge a couple of hours before our flight? I'm reading the bus is about 10 minutes between the two, but I also remember Narita being quite spread out just walking from Transit to the single lounge.

If possibly how long would it take to get from the Sakura lounge in T2 to the ANA lounge in T1?