Just equip whatever your highest light gear is, even if it's blue. The higher your light, the greater chance of higher light gear. If you have a 285, and get a 295 blue, wear the blue instead of infusing your 285 up to 290/291. Then after you get more high level blues, infuse them to your legendaries. The highest blue I ever had drop was a 299, and it was when I was 297 light. Basically, don't use blues to infuse anything unless it will infuse to the full light level. Until then, wear the blues.