Best Time to Play Ishin?

With Ishin taking place in the past, is there a good or bad time to play it? I started with the two Judgment games, then 0, and now playing Kiwami. Wondering if I should jump to Ishin next since it’s on sale.

Also, is it worth getting the deluxe version for the added weapons and materials? Will it save much time on the plat grind?