I would wait if I was you, administrative really isn't a big improvement and the cost to get out of it and into absolute monarchy is high(have to backstep to despotic monarchy then to absolute) unless you actually have the goal of either becoming a constitutional monarchy or heading into the republics. I prefer absolute especially after 1650 when holy war and excommunication CBs are gone. Absolute monarchy, enlightened despotism(the next in the step after absolute), republican dictatorship and the revolutionary governments are the only ones that get Imperialism(standing CB on everyone and 50% infamy cost, best when the beloved holywars disappear and tribals/hordes/pagans are annexed :*/