You do not say how deep.
304 work hardens and if possible you should avoid pecking.
Also your feed is a bit low, my calculation gives around 0.0016" per tooth which is maybe not enough to get under the work hardening. I think you should be able to take this up to 0.005" maybe even more.
And I wonder about piloting at 0.36" then drilling at 0.69", you might find the larger drill chatters badly and the edges chip. I would be tempted to go straight in with a split point drill possibly running slower than your speed but with a good feed and lots of coolant. The risky parts comes when it breaks through, you really need to get plenty of coolant there and directed to the back side of the hole if possible as things can get very hot at this stage.
It seems you are using the 3/4" mill somewhat as a reamer; this is okay and will certainly give you a better hole than a drill can produce. Here I would consider using a corner radius endmill, the sharp corners on a regular mill get much hotter and can be prone to chipping.