How reliable is execution timing?

For example if i Instantiate object, then immediately call RPC on it
will it guarantee that its always called on same frame before Start() for all clients?

var my = PhotonNetwork.Instantiate("my");
my.RPC("Constructor",param1,param2,param3);


or is it if on bad network it may happen that object is instanciated, then on other frame "Constructor" called?

(Sorry I posted this to wrong topic, should go to PUN)