Using cheap loads to get it close is a good idea. My advice is don't be scared to shoot a couple extra TSS loads on the initial sight in to make sure you get it "perfect" for how you want it. A little pricey on the front end but each year after, 1 shell to make sure you are still hitting your mark and you are good to go.
If you are really worries about cost - get it close to where you want it with bird load, shoot a TSS shell to ensure you are on, shoot a designated non TSS load and take a picture of where the pattern is. Moving forward, if you want, you can just shoot one of those non TSS shells and if the pattern is "off" in the way it is supposed to be you are good to go. This way isn't as exact but is definitely cheaper.