Umm first of all I definitely recommend making isshin permanent because he's absolutely the best single pve partner you can get. He's also pretty damn amazing for pvp.
Secondly like I said on your other post I'll keep an eye out for when's a good time to top up and get the most bang for your buck. You don't happen to remember what your last ultimate top up event looked like do you? If there's no major spenders in your set of servers then that's always a really good one.