As I have made some experience in this game, I would advice you to rather than start a new agency this young, to find an agency with some more experienced sleuths to have a place that could support you when you are in your early growth. I think you will need your money for other things than running an agency, and there are some substantial benefits of joining and "older" agency, as they might help equip you with equipment that you would otherwise be unable to get, your experience taken into account.
Also, they might help you in other ways you might find very useful, and they might even give you some good friends.
I am not writing this to you because I would like to hire you, as my agency is not hiring ;-)
Also, I am not writing this to offend you, but to try to kindly give you some thoughts. You might have your own opinions and own thoughts about your choices, and I might be totally wrong in my suggestions.
But, having been a young unexperienced sleuth once myself, I thought that I would share my opinion with you :-)
Best regards and good luck with whatever the conclusion you end up with.
I hope you will continue having fun with Sleuth.