What is the test for "mutual combat" in the context of a defendant's claim that he acted in self-defense?

The term '"mutual combat,"' as used in the context of a defendant's claim that he acted in self-defense, "means not merely a reciprocal exchange of blows but one pursuant to mutual intention, consent, or agreement preceding the initiation of hostilities." (People v. Ross (2007) 155 Cal.App.4th 1033, 1045.) "In other words, it is not merely the combat, but the preexisting intention to engage in it, that must be mutual." (Ibid.) The agreement may be express or implicit, but "there must be evidence from which the jury could reasonably find that both combatants actually consented or intended to fight before the claimed occasion for self-defense arose." (Id. at p. 1047; see also CALCRIM No. 3471 ["A fight is mutual combat when it began or continued by mutual consent or agreement. That agreement may be expressly stated or implied and must occur before the claim to self-defense arose"].)