The size of a time-slot in a simulation has an effect on accuracy and on computational resource requirements. Trying out possible sizes (1s, 1m and 1h) I identified 1m to be the only smart choice. Defining this at an early point of the method section would greatly simplify subsequent issues like mathematical denotations and data collection. Is it allowed to do this or does all generated empirical data need to be packed into the result section?
In my thesis, I kept similar issues separately, but referred the reader to the results section discussing results and conclusions from side experiments that lead to certain decisions. This allows to use the results before they are presented in detail.
In your case, the methods could read:
Preliminary simulation to determine time slot
Based on teh results of 1. (see link to results section), a time slot of 1 min was chosen.