Although I always recommend the ammonia bottles during fishless cycling, I generally don't for tank "ticking-over". Reasons being:
1) You have no clue how much ammonia you will need in terms of ppm, you could "understock" your tank by measuring out a smaller amount.
2) You will need to add the same amount of ammonia every single day, which has 2 disadvantages, forgetting and money; you can use alot of ammonia very quickly on large tanks.
3) You could just throw a prawn in a cut-off piece of stocking/tight and be done with it, no daily adding and no substantial cost. You don't know how much ppm you need anyway, so guessing with a prawn would be no different.
4) When the prawn has disintegrated, just chuck another one in, easy. It may not be the most accurate way of doing things, but it works, and it's cheaper and less time consuming.
Not to say adding ammonia isn't wrong, far from it, I just prefer this method as I'm rather lazy.