need advice on my cornrows

YOU WASH YOUR BRAIDS WHILE DEY ARE STILL IN YOUR HEARD,, DAT MITE BE DA REASON WHY DEY WONT GROW,,,, HOW OFETN DO U DO DAT, GREASE GOTTA STAY ON YO SCALP FOR A CUPLE DAYS TO MAKE IT GROW, I AINT NEVA HEARD OF WASHING YO HAIR WIT BRAIDS IN, AND I GOT BRAIDS TOO, AND I PERMED MY HAIR AND NOW MY HANGTIME IS HANGIN KINDA LONG

My question is kinda long but I dont know much about this and i'm sure the experts here can help a brotha out

Hey people im a 20yr male. Hair type 4B (coarse / nappy i think?). I waited quite a while and my hair finally got long enough to get my cornrows. I dont have any "hangtime" so at the back of my head the braids barely hangs off where it starts to grow. I know i have to be patient and over time the hair will grow.(no extensions)
But ive been braiding my hair ( and taking it out of course ) for about 4 months now and it looks the same as it did from day one shouldnt i see a difference now?

I dont really know much about hair so i just go to the salons up in Harlem, they take the braids out, give me a wash, apply some oil, blow dry and rebraid. In between these trips i just wash my hair in the show with a stocking cap on.

what else should i be doing in between the periods when i get my hair taken out? are there oils, shampoos, conditioners i should be applying? ive also heard theres vitamins that help. and is it ok to wash the hair every day ? please if you guys have any advice dont hesitate id greatly appreciate