need advice on my cornrows

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

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