I think you have to take into account a few factors,mainly like what Adrian has mentioned, the amount you’re setting aside every month And the costs that comes with every trade. A few other factors to consider as well could be the price you’re paying for the stocks, sometimes if you consistently purchase a particular stock at a rising price, you’re averaging up your holdings in it and if all’s good then its still ok bit if you were to miscalculate, you might be in for a surprise. Vice versa for a stock at a falling price. Investing on a monthly basis is still possible if you have a watchlist of stocks and if one of the stocks happens to hit the target price you’re comfortable in paying and by all means. This way you’ll be able to work your money more productively. Cheers to a wonderful investing journey ahead!