The idea of early c7-c5 in Nimzo-Indian defense
Speaking in general about ways for Black in Nimzo-Indian defense and ways of development of pieces, there might be singled out some ideas such as blockade by means of d7-d6, e6-e5; counterplay in the center - d7-d5 and (or) c7-c5; queen-side bishop fianchetto b7-b6, Bc8-b7 (or Bc8-a6). Looking at the possible and popular moves of Black after White's 4th move in Nimzo-Indian defense, we can see that they are: 4. ... 0-0, 4. ... d5, 4. ... c5, 4. ... b6, 4. ... d6, 4. ... Nc6 and 4. ... Ne4 (I do not take into serious consideration rare and not very popular moves like 4. ... c6 etc). Some of the mentioned moves are more popular and more advisable, some less - but much depends on the variation which White chooses at the 4th move. For example, the move b7-b6 which is very good in Samish variation (4.a3 Bxc3+ 5.bc b6) is not so good (and therefore not so popular, but still playable) for Black in Classical variation (4.Qc2 b6 5.e4). But there is a move, good by itself in general and playable for Black in all main and popular variations which White chooses at the 4th move - that is c7-c5. The only exception is 4.a3 - but anyway, after 4. ... Bxc3+ 5.bc comes 5. ... c5. The whole point of the c7-c5 conception is that Black often has a possibility to transpose the game from one variation into another, and to combine the whole thread of play among numerous subvariations, looking for the most suitable and preferred ways which arise after each move.