People tend to check in during these times:
The only consistently good bus operator to Kerala
Have your printouts ready if you have an online reservations.
The service is getting worse and worse, I'm pretty sure a lot will testify to that, especially the travellers of that 7pm postponed bus yesterday and getting ditched at Kollam.
The Bangalore to Trivandrum 7pm bus, they'll tell you'll reach by 8. I've reached at 9 once and is always been around 11-1 every other time. If in a hurry, better not choose this bus.
You just need the e-ticket now, just show the phone, saves the trouble of taking print outs