That's good for 8th grade, although my team has a guy who runs a 49 and two others at 51. Its a really good 4x4 team, especially for a school that graduates 75 students a year
Pretty solid time, just keep at it, you'll need 49s ish to run D1 college (I run 800m D1). You still have a lot of time though. Work hard and the results will come.