Listening to Subsystem on Ready?

Hello im having a problem which is that i recenter the player un the level in a way that the head is in the place i want independently wheres the real player

but seems that if the XR Subsystems havnt initizliced yet it head remains at v3 zero
what i do is just substract the rotated local position of the head and add it to the rig

Is there any way to listen to Subsystems Ready/Initialiced
because the problem is giving me this is this
i can not find a way to await it to finish wich does in 1 or 2 seconds
but i dont want to hard code a waiting in the code for this

 

Cool thanks a lot!