If he's already tired and it is 1145 -- that makes 5.5hours of A -- then I would put him down now. And, I would aim to have him in bed for 5.5h of A every day then, trying as best as possible to keep it really consistent. He should sleep 1.5h for you on this A time I would think, going on his past nap behaviour; so waking at 115, that still leaves a good 5 - 5.5 before your ideal 630 bedtime.
Otherwise, I think you are pushing him into OT, then leaving a shorter space before bed, which may give you some great catch up nights, but in the long run, isn't that good for him, kwim?