My hair is about 4 inches long is that enough to get the full cornrow effect?

or would u advise me to dread braid it 1st n let it grow longer?

My hair is about 4 inches long is that enough to get the full cornrow effect?

depending on who you get to do it, this may be long enough. You may find though that it gets frizzy faster because it is shorter. I dont know your hair texture so thats tough to say but if you can find someone to braid it- go for it! Hope this helps!