First, don`t buy all your inventory at one time. It reduces your profit margin and ties up all your available operating capital until you sell the product. You also pay higher holding cost ( warehousing costs ).
Heres an example of what I mean. Let`s say you have $15,000 available to buy 1000 do-dads. You will sell all 1000 do-dads over a two month period and realize $3,000 profit on an initial investment of $15,000. But, you also have to find a place to store 1000 units until they sell.
Now let`s change this a little. You will still sell all 1000 do-dads over a two month period. But instead of investing all $15,000 at one time, you invest $7,500 and buy 500 do-dads. Just before you run out of inventory, you take $7,500 from the sales you`ve already made and buy another 500 do-dads. You then sell all of these as well. You still realize a $3,000 profit. But now you are realizing a $3,000 profit on an initial investment of $7,500 instead of an initial investment of $15,000. You also still have $7,500 in the bank and can reduce your holding cost buy having a smaller inventory.
As far as being able to fill customer orders, you will need to determine a realistic delivery schedule to customers.
---The older we get, the more excuses we make for not chasing after our dreams. But truth is, goals are attainable at any age.