First .... remember -- free advice is worth what you pay for it!
Although it's pretty cool that you were able to get a type with only 300 hours, you still only have 300 hours. I don't mean that in a bad way .... because at some point, we all were there.
As previously mentioned, you could through yourself out to the contract market and try to build time that route, but .... I don't recommend it. You won't learn anything. It might be "cooler" to get out of a jet on the ramp instead of a 172 or Seminole, but ... you'd be little more than a seat filler.
Instruct! ... singles and twins (if you have an MEI). You'll build time faster and you'll learn in the process. Although multi jet time is good to have in your log book, that will come. With 300TT it's more prudent to build the foundation and there are fewer better ways to do that than instructing. Good for you that it's not a bad market right now for flight instructors.
Whatever pans out for you, I wish you the best of luck!