Start Small or Large?
 

What are people's thoughts? Is it necessarily too stressful to start a snake off in a big enclosure? Should I start with a small snake in a smaller enclosure and get bigger, or should I just get a large enclosure so I'm not replacing the tank?

Size isn't the factor when it comes to stress, rather the amount of open space. There is a moderate tendancy for many people who are just starting out to very strictly follow the guideline of cool hide, warm hide, and water bowl, leaving vast open swaths of open air in between those basic necessities. As an example, consider that NE Herp's bioactive plant kits for 20 long aquariums contain 8 to 9 different plants.

Large cages also tend to have bigger gaps that are easier for tiny baby corns to escape from. Because of this, I do recommend smaller tubs or aquariums for very young snakes.

With a larger, more complicated cage arrangement, you may be inclined to clean it less often than you would really need to do so, because of the time and effort involved. So after a period of time, the cage would become dirty enough to attract insects.

But if you have loads of time on your hands, maybe that won't be a problem for you.