Most Opponents won't allow you to have two d4 and e4 pawns side by side. You could flip the board and try to see what they see.
When should my knights not be on c3/f3? also pawn structure

I have worked out some magic. Every post on this page that I post goes under post #1 and mimmediately marked 60 min ago.

Generally speaking your knights are going to be very happy starting life on those squares. They are fluid in that that they have access to the central squares and are working well defensively. As the game progresses you should try to improve the position of all your pieces. If you can secure an outpost further down the board for one of your knights for example you could then also advance an c3/f3 at a later stage.
Openings like the Nimzo are from the hypermodern school of thought whereby they try to control the centre from afar and later perhaps push with pawns.
A book that I would recommend for you would be Chernev's Logical Chess. This will give you a good insight into opening play and strategy. There are also modern move by move equivalents but the author just slips my mind but type move by move chess in Amazon and it will pop up. The vast majority of chess players would recommend this sort of approach to the opening as opposed to memorising a particular opening and I agree.
There are 2 cases, when you don't want to put them to c3/f3 or c6/f6 (as black)
1. When you can't put them there. In openings, like the slav defence black plays c6, and therefore he has to put his knight to d7.
2. When you put a knight on the c or f file, they block those pawns there.
Very often you want to play first c4/f4 or c5/f5 before you put the knight on c3/f3 or c6/f6.
If they let you play e4 and d4, play that, develop your pieces into the center then open the position and attack. (But you won't get such positions often.)
You shouldn't play the nimzo indian yet, first play the classical openings.

The most difficult part of all this is when to play Nge2. Here is an example of Nge2: Grunfeld 1 d4 Nf6 2 c4 g6 3 Nc3 d5 4 cxd5 Nxd5 5 e4 Nxc3 6 bxc3 Bg7 7 Bc4 c5 8 Ne2. The knight goes to e2 to avoid a ...Bg4 pin, or at least to allow the ...Bg4 to be attacked by f2-f3.
In the Carlsbad QGD, White doesn't want to play Nf3 too soon. Later, White has a choice of Nf3 or Nge2.
Your unease about placing knights on both c3/6 and f3/6 (both blocking in the c and f pawns) is well placed. As a very general proposition that set up is thought to be a bit sterile.
So look to get one or other of the pawns advanced first or manoevre one or other of the knights elsewhere.
But don't get hung up on this. It is not a really big deal, a knight on c3/6 or f3/6 even with the pawn blocked in behind it is out and into the game, has strong influence on the centre and has gained a whole lot of mobility (which a knight needs more than most). You have maybe made it a percentage point or two harder to find some good plans going into the early middle game but that is all. Compared, say, to neglecting the development of a knight altogether that is very small beer.
I always try to post them on those squares. Yet doing so feels uncreative... novice-ish. I know of openings where knights get placed elsewhere, yet I've never been in a situation where I thought 'of course I shall place this knight on d2, thats it best square right now!' unless c3 was under attack. Knights sitting on those square also completely blocks my c and f pawns, which cant support my center pawns at all (should they???).
Say my opponent waste time in the opening, like completely. I will alwlays play e4 d4 Nc3 Nf3 in that case. Rarely do i get to, as most opponents challenge the center, but in that case I always *try* to get that set up. Is it even effective? It feels boring to play now and I feel like its hindering my growth. The position reached in the Nimzo Indian is so alien and scary to me.
I'm not exactly sure what Im asking. I guess id just like some higher rated players to listen to this ramble and give me any input at all that's helpful or thought provoking.