I just checked the two days merit shared data manually for 29/30 September and found that 16 merits were shared. So by adding these 16 merits, the effective merits shared in the month of September becomes 374.
You just checked posts written in the last two days (September 29th and September 30th) right?
I am asking because to you would have to check all posts written last month in order to get correct number because some post from lets say September 10th might have been merited on September 30th and you would have missed it if you only checked those last few days. That essentially means that your number of merit shared might be higher than 374 and for that reason its best to wait for Friday and check Merit Dashboard to get exact numbers.