When to buy breast milk pump?

I bought a week after my EDD. However, I have one spare pump to standby - just that the suction is not strong enough for me. You don’t need to worry about supply. Your body will produce milk naturally. It’s normal to have little milk at the start. Just don’t give up and continue to latch and pump despite lesser milk. Give your body some time to adapt too. After some time, the supply will be sufficient.