The distribution of the remaining supply is really not normal anymore and is only positive since you clearly cant have a negative balance. My approach is to explicitly simulate the weekly remainder but having a check for less than 0 remainder, in which case, I force it to take the weekly delivered amount as the left over amount for that week.

remainder = 0
num_exp=100000
delivery = 47
res = []
for exp in range(1,num_exp):
    start = 74
    remainder = start
    for week in range(1,12):
        remainder = remainder - np.random.normal(50, 10)
        if (remainder <=0):
            remainder = delivery
        else:
            remainder += delivery
    res.append(remainder)