thats what i always do. Send a scout after i build my barracks to where they were normally build the 2nd base. Delay that for as long as possible. I dont see too many early spawning pools but when i dont see an expansion anything at the expansion yet i always scout the base.
Thats probably where i am lacking at, widow mines. I use them... just not very many.
EDIT : Do you think it is worth building an engineer bay in the expansion spot early? or does that hardly delay you?
also my statistics this season are retarded. 84% win vs protoss. Last season i was 42 vs protoss lol.
The eng bay really depends. It can delay if the Zerg is playing extremely greedy and just droning. It can also force them to make zerglings to clear it quicker instead of more drones. Then you just have to worry about the zerglings coming to do damage. And some players will just take their 2nd where their 3rd would normally be if you do that. It is harder to defend but they will only lose a few seconds of mining time. So if it doesn't delay enough you have just wasted those minerals and you run the risk of losing the scouting scv in the process. I prefer to set my worker on patrol in a circle so their worker can't place the base down, and then I pull it before their worker can kill mine.
A fun thing with widow mines is packing 2 in a medivac and dropping/burrowing 1 at the main and natural mineral lines. Especially if Zerg hasn't researched lair yet, it will take a bit before they can see the mine and destroy it. They will have to put a spore crawler down to see it. You should get 1-3 good hits in or at the very least he will pull workers and lose a substantial amount of mining time.
Timing attacks work well against greedy zergs as well. For instance some zergs will go 3 base Mutalisk play and literally make no units other than a few queens for injects and drones. If you scouted that and left before their huge round of muta's come in you win. It's tough if you don't know though. I have done 3 base muta's and made no offensive unit until like 10-11 minutes and I won because my opponent didn't punish me and my economy was far ahead of his.
But just scout a lot. Scout at the beginning, leave your scv near their base and send it in again later, use a scan if you need to if you don't know what their tech choice is. Zerg is reactive, so they can switch tech quickly. They will react to what you are making in mid game. So you need to scout after big engagements that you win to see if they are just doing the same or switching.
The creep kinda sucks. It gives them map vision and their units move quicker on it. Other than wasting scan after scan, some Terrans like to build 1 Raven since it is a detector and then clearing all of the creep tumors as they go across the map.