Mad Max countdown

Tonight I squatted heavy sets. I started too light at 245#. I ended the last set at 275# for six reps. I also did four sets heavy dumbbell lunges before squatting so my legs were pretty fatigued. I know that 275# on the last set for six reps isn't impressive territory, but I am just getting back into squatting regularly and I am a little hesitant about doing something that might cause injury. At any rate I don't really have any idea of where I might be able to max next week - I don't even know what to hope for. I do know that it won't exactly be impressive, but I will show progress and have a baseline to judge my progress by.