Just make sure the last thing you do for the week (in terms of "Powerful Rewards") is the MIDA quest. Do one milestone, check your gear to see what can be upgraded with blues and upgrade those so your base power level goes up, do another milestone, upgrade again, etc. Then grab one of the clan rewards, upgrade, etc. Finally do the MIDA quest and it will be as high as you can get it this week.
Also, MIDA is pure ass for PVE. You should do the Zavala quest to complete two strikes (which is a pre-req for the Nightfall anyway) and choose Nameless Midnight as your reward. I infused my first MIDA (~285 power) into NM, then made sure my second and third ones were both 305 and infused them into NM again and Manannan SR4. Power level doesn't mean dick for pvp so just re-buy the MIDA from the vault to use it.
And Manannan SR4 is the Nameless Midnight of energy scouts; it has Explosive Payload just like NM does, *not* High-Caliber Rounds. If you want HCR for the energy slot too, get a Uriel's Gift or Tone Patrol (Pleaides Corrector is better, but you missed the faction rally I'm guessing). PVP meta seems to be MIDA/Uriel since it doesn't make a lot of sense to put scouts in both slots.