You should get whatever you want. Are you going for determination or spell speed or crit rate? Judge on what is best for your play style and go in that direction. If you want specific allagan drops then hold off from getting those pieces and perhaps you will get them during coil. If you don't plan on playing coil then go for what would suit you best. If you get the body, then the next piece you should get is the head. That is a total of 5 weeks to be optimal as you'll have to use strat or vanya in its place. Gloves and boots are cheapest only taking two weeks to get. The pants are more expensive, but add quite a few stats and only at 3 weeks. If you want crit then go for the rings. The choice is yours.