when do i pick spinach

you can pick it when you want only pick what you need to use and it should keep growing

I think you could pick it anytime now. If you want "baby" spinach than it will be the right size. You can let it get bigger and fuller if you want but spinach doesn't like hot weather, so if it is getting really hot you will want to harvest it.

I am growing spinach for my guinea pigs and pick a few leaves every day and it just keeps on putting out new leaves. It is in a shaded spot that only gets early morning sun and this stops it from bolting too early