WRT when you start the company - I only have experience from the UK market, but here you're doing a tradeoff; on the one hand there are a lot of programs and benefits for startups (like SEIS tax relief), so it's beneficial to be 'young' for as long as possible, but on the other hand, some big companies have purchasing requirements that, to protect them from immature, risky startups, only permit them to purchase from a company that has been around for a certain period of time, often years.
As a caveat to that, however, most people tend not to use incorporation date to decide whether you're a startup - start of trading, or fundraising rounds are the most common alternatives, so if you've not done either of those things your previous startup would be, for most purposes, a clean start.
I personally would set up a new one just for cleanliness, but then that's a very cheap, easy process in the UK, I don't know if that's also the case in the US.
As a caveat to that, however, most people tend not to use incorporation date to decide whether you're a startup - start of trading, or fundraising rounds are the most common alternatives, so if you've not done either of those things your previous startup would be, for most purposes, a clean start.
I personally would set up a new one just for cleanliness, but then that's a very cheap, easy process in the UK, I don't know if that's also the case in the US.