Whats a good estimate for how much my homeowners insurance would be if I’m a first time buyer, my home is around 300,000. and I have good credit, plus the home is in a brand new developement. I just want an estimate. Thanks.

You are open for a pretty good range of values, depending on where you live and what coverages you are looking for.
Typical annual premium will be $500 for lower coverages in a not-so-risky area (risky is coastal, Southern Florida, fire or earthquake zones, etc).
If you already have auto insurance, call your agent to have him/her discuss your options; there are a lot of them. Make sure to use an independent agent that can write you a policy with one of several different companies. That will give you the flexibility of premium and coverage options.
A good agent will spend 30-60 minutes with you to make sure that they understand all of your insurance needs (car, home, home-business, kids, pets, etc). If they just spend 2 minutes to get the basics from you, keep looking for a better agent.