Gravity brake bleed not working

Have new master, all new slaves, empty brake lines, everything is dry except for the master which I bench bled and is full of dot 5. Have slave bleed valves open down below.
No fluid will come out of the master.
Do I need to push my brake pedal down and put a wedge in to keep it down? Even when I was mounting the master after bench bleed no fluid was coming out of it before even attaching brake lines.