Hey,
untill the DMVPN hub is not configured as the static VTI, i.e. specific tunnel source and tunnel destination is not configured on the hub, the initiator will always be spoke.
the whole purpose of having a dmvpn tunnel is so that any spoke can connect to the hub(given the spokes are configured to connect to the hub) without having to specifically define the spoke's ip address on the hub. Hence, the tunnel would always be initiated from the spoke.
please see the below document for further explanation:
When the spoke router starts up, it automatically initiates the IPsec tunnel with the hub router as described above. It then uses NHRP to notify the hub router of its current physical interface IP address.
http://www.cisco.com/c/en/us/support/docs/security-vpn/ipsec-negotiation-ike-protocols/41940-dmvpn.html#dyntun
