Well, the answer to your original question may be found in monitoring your levels.
Testing first thing in the morning, before bed, and before and two hours after meals should give you a good idea on what's happening, and you could do some esperimenting with the timing of your dose as well.
You probably know already, but if you reduce carbs and you are on gliclazide, there is a possibility of going too low. So please always carry your meter and some quick acting glucose on you, you don't want to have to navigate stairs while half asleep and hypo.
You could also apply for a free 2 week sensor if you haven't used one before. It's a wonderful tool to find patterns, and with the two weeks you could do one week of gliclazide in the morning and one week in the evening and see what difference it makes.
Mind, while the Libre is wonderful for spotting patterns, it's not always trustworthy for absolute numbers, so I'd always verify a low number with a fingerprick before treating as a hypo.
According to google, the action time of gliclazide varies a lot depending on if you take it with a meal or in between meals, so this may be something to keep in mind as well.