When prostrating during prayer, how do I determine if it is the first or second prostration in order to move on to the next rak'ah?

If doubt recurs in prayer, it should be ignored to facilitate ease and remove hardship. If doubt recurs frequently, it does not matter; take the higher number and prostrate after the salutation, unless you are certain. However, if doubt occurs occasionally, take the lower number and perform the prostration of forgetfulness, based on the noble Hadith (definition): "If one of you doubts in his prayer and does not know whether he prayed three or four [rak'ahs]? Let him cast aside doubt and build upon what he is certain of, then prostrate twice before he makes the salutation."