Need your advice sir

was looking to give p7 in december only but i felt that i have alot of time on my hands and should push through for another like perhaps p4, p6 is out of my radar as its quite long and takes time to comprehend and p5 is not my subject really, what do u think is it good option if i go for p7 and p4 and start studying for them super hard , and how is the course length of p4 and p7 compared to other optionals?