Where I live , the cost of contracted blown upgrade for 700 ft is very close to cost of a DIY job with 0 bags of a blown to install including free blower at HD.
I find when I'm in my 4/12 attic a foam kids snow sled laid across the joists is a lot easier on the ribs and back than a piece of plywood... and much easier to move. Take 2 and take a cell phone on a lanyard if it's a big attic, and a jug of cold water
Also find a bump cap keeps the roofing nails out of the scalp.. hard hat is too bulky. You want to be up there when the temp is under 75
Check your soffit ventilation and joist liners before you add insulation