I was there to collect OCI for my spouse 2 yrs ago. It is good that you are making the trip as soon as they got your docs back. So misplacing excuse can be ruled out.
From my experience:
Take a print out of online status message.
Passport (Indian and US)
Be there by the time they open at 10 AM.
Take the number (it is tucked into the corner..you can not see it unless u look for it)
Drop the Passports (takes less than 2 minutes if you are first in the Q)
You can go and have fun in the city. Google for Pavani in Houston. Nice Indian restaurant with large buffet.
Come back to consulate around 3:30 or so as there will be a line for collecting passports.
They're supposed to open window for OCI collection around 4.
Don't be surprised if they're late by 15-30 mins. Common practice. I've seen people banging on the windows asking them to open as they're late by 30 mins...and people have to head out to beat evening traffic.
And also don't be surprised if they open some other window than the one marked with OCI passport collection. People had to literally run from Q to the other window. The person last in the Q might see them opening the other window and could reach there first. Happens all the time. Very confused people out there.
Make sure you check the passports thoroughly before leaving. The visa sticker's name/dates might be out of alignment. Normal. Nothing to worry.