Is that a sigh of relief or was that a meh?
Don’t Stockpile Valor Points
Unless you want a 4k Justice Points. All Valor Points currently in possession are becoming Justice Points. So any Valor you have when the patch goes live will not get you a head start on ilvl 378 Valor purchases. The extra Valor isn't converting past the normal 4k cap on the PTR, so anyone whose Valor and Justice Points sum to a total over 4k will simply lose the excess points.
If previous patches are any indication this new patch will be a great time for gearing into ilvl 359 and quickly getting alts to fill in holes in raid teams.
Do Stockpile Crafting Materials
If you are looking to have the new agility BoEs made quickly. The new crafting recipes for the ilvl 365 gun and the ilvl 365 agi two-hander will require expensive materials and they will only go up in price once the patch hits. So start gathering up any mats that you will require now. The demand for materials will force existing crafted items up in price as well so you might be able to save some gold by buying your new leg armor pre patch as well.
The role of Chaos Orbs (the gun and polearm both require five) remains uncertain. Blizzard has merely said that they plan to make the orbs BoE in “a future patch” and not 4.2 specifically.