I'm super nervous to shoot BIF. I feel like all my shots are going to come out blurry because I'm having a hard time imagining having enough time to track and shoot while remaining steady. Even the IS takes a second to kick in. You shoot tripod/mono for BIF?
Take it slowly..
IS has little value for BIF because your shutter speeds are in 4 digits almost always.
Unless a gimble head, tripod will not be very useful for BIF.
Tamron is "light" and can easily handhold for BIF (with practice)