Server opening event goes for roughly 2 weeks, I believe, with 15 pieces a day if you recharge enough. 14 x 15 = 210. 30 to unlock him + 50 for 3 star + 100 to 4*. That's 180 pieces you would need so even at only 12 days you could get him to 4* with that. If you were in an early enough server there was also the lucky stars event with PB Sasuke and him where you could earn another 80 pieces directly. Other than those it is luck based in the limited seals packs.