Let's say I have a Pyramid Turtle in attack mode, I activate reinforcements and attack a Revival Jam with Umi on the field (1700 vs. 1700) we both die. I summon Ryu Kokki to the field with Pyramid Turtle's effect. Can my opponent activate Revival Jam's "optional" effect by announcing his intent to pay the 1000 life points or has he missed his chance because Ryu Kokki has been summoned after he was sent to the Grave?