Better to give dose early or late?

My cat has been on Vetsulin for a few months now, doing great. Started off at 3 units twice a day for a coyuple months, and then about two months ago lowered it to 1 after a hypoglycemic incident, and since then there's been no issues. I've been giving the dose generally around 6:45 AM/6:45 PM, usually within 15-30 minutes of 7 PM on either side, with only one case of having forgotten the evening dose and realizing at 8, so I just gave it then and then staggered it so it was a little later the next morning until back on the usual schedule.

This Saturday I have an engagement at 6 PM and I'm trying to figure out the best option... should I give the dose a little before 6, or wait until after, probably around 8? This is the first time I've had something come up that interrupts the usual schedule.

Any advice on this is appreciated! Thanks.