How long should I wait to detect coolant?

[Zahndkile]

I have a 2001 Pontiac Aztek that leaks coolant pretty badly from the intake manifold gaskets. I can see it running down the side of the engine but I want to be 100% positive that the head gasket is not leaking coolant into the engine before I replaced the intake gaskets.
Like an idiot, I completely forgot to get the sample bottle out before I started draining the oil last night so it has a fresh oil change in it and now I'm wondering how many miles I need to wait before taking a sample to send to Blackstone and find out if there's any detectable coolant in the oil.
Any thoughts? I'd like to wait no more than 1,000 mi because the leak's getting pretty bad and I want to go ahead and fix it soon but I don't want to send in a sample that isn't going to be able to detect a small head gasket leak.

 

[KGMtech]

It won't take 1000 miles, I would expect if there was going to be internal leaking this will show up in less than 300 miles.

 

[Zahndkile]

It won't take 1000 miles, I would expect if there was going to be internal leaking this will show up in less than 300 miles.

That's reassuring. I'm pretty sure there's no leakage because I've never seen condensation on the underside of the oil cap. But I want an analysis just to be positive.
I'll probably wait a thousand miles because that doesn't take very long and it won't get to it any sooner.