Currently, the boxes you get from invasions scale up in item level if you don't open them until the desired level. For example, you could get a box at level 10, open it up at lvl 100, and get item level 700+ gear. So since this gear appears to be like time walking gear, the theory then becomes, if you wait til level 110 to open the boxes, you may or may not get a full set of gear scaled to level 110 instead of level 100. I also recall there being a bug with time walking gear where if you threw it in void storage, it would reset the item level on it, so maybe if you chuck the off pieces you buy from the vendor into void storage, then level to 110 before taking it out, it could possibly end up giving you the level 110 gear. Just thought I'd throw the idea out there for others who have lots of time to kill and might want to get an edge at the release of Legion.
Sorry in advance if this doesn't end up working.