startin my dreads-got a thickness question

Ok, so I KNOW I'm supposed to just let it ride but I do want to know one thing...I'm starting my dreads using the TNR method-after reading about this method in the forums it seems the best fit for me as I prefer the thinner, slightly more neat and tidy dreads. This being said, when sectioning my hair for twisting and ripping, if I want them to mature into the thinner type (not much thicker than a pencil) then how much hair should I gather per section? Am I right in understanding that dreads will naturally get thicker as they mature? I don't want no congos and I do prefer the thinner ones so I want to start it off right. Thanks!
updated by @raegan-belew: 01/13/15 08:42:29PM

u weant the root sections to be about pencil size but your looiking at over 100 dreads probable and that will mean harder to keep track of and a greater chance at accidental confgos so id concider a lil thicker like 1/4 inch or lil more try to get 60-75 its still alot but will be easier


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