Have you tried lysing cells and analyzing lysates by SDS-PAGE and/or Western blotting?  You might want to run a series of pilot experiments varying ODs from ~0.6 to 1.

I would run a growth curve experiment. Grow your cell culture at desired temperature (this may also need adjusting) for 4 hours taking a sample every 30 minutes and read. then check at which OD your curve was in a positive growth phase. Then do an induction study of time and IPTG (if this is the inducer) concentration. Once all samples are collected run on a SDS PAGE gel if you see no over expression at the desired size try lysing the sample by sonication and re run the samples. Temperature, time, IPTG concentration all have an effect of protein expression. I have 1 protein that must grow at 32 degrees Celsius and once induced grow at 28 degrees Celsius. You need to find the optimum conditions for your protein of interest.

Thanks. I need run a growth curve experiment.