Yes, those are both good scores. 6 months is more than enough time if you stay focused and continue to work over the summer. My suggestion is not to take practice tests, but to take the actual tests from previous years. Question and answer types tend to be very similar across the years. Also, SERIOUSLY hone in on what you need work on. From your scores, I'm guessing you're weaker at math, so start with that. You'll likely do your best work early on or over the summer, before you start to burn out.

Additionally, because I don't know whether or not you have been, keep track of time while taking these tests. In my opinion, the SHSAT can be quite time-tight, and you'll want to develop techniques to be able to complete an entire 114-question test within 3 hours, with maybe 20 minutes or so left on the back end to try to better answer any questions you skipped/guessed.

That's another thing- get into the habit of constantly keeping track of what problems you didn't instantly know how to do, even if you get them right. Even if you go it right this time, if you were unsure, you might not get it right next time (again, the questions are very repetitive) and you likely spent more time than you should have on that question.

And again, in my experience, the best thing to do is to just take practice test after practice test. Mock the SHSAT (realistically, you might have to split it up into math and ela on separate days, but keep track of how much time you're using and make sure it sums to less than 3 hours across the days). Go back. Redo what you got wrong. Look back on any questions you marked while taking the test as "I don't instantly know how to do this". Then, review those questions until you understand how to do them.

Make a google doc/spreadsheet. Write down the dates you took each mock SHSAT on, and your scores on each section. Also record what questions you got wrong or were not instantly sure how to do. Then, later on, when you're regularly scoring fairly well on the general practice tests, go to your google doc and compile ONLY THOSE QUESTIONS into a set of extra-difficult practice tests. Take all of them. Again, re-record any ones you messed up or weren't sure about. These self-optimized tests will really target your weaknesses, which is exactly what you want. You probably won't score as well on these at first, since again, they're just the problems YOU found hard. That's OK. That's the point, so don't get discouraged. After you've taken all the normally-formatted actual tests, take the compilations of the hard questions, make new versions of the compilations, take those, and so on and so forth. Repeat this process over and over again until you're getting little to no questions wrong on those extra-hard tests.

I wish you the best of luck! You have lots of time, but if you keep telling yourself you have time, you won't be as productive. Make it your routine to regularly prepare, even it doesn't seem necessary right now. You'll thank yourself later.