Image of my test results performed by my SamKnows box:
It runs tests at midnight, midday and 6pm. Then it does hourly between 7pm and 11pm.
The results almost always come back at 71Mbps or 74Mbps, with little obvious correlation to peak hours (8pm - 10pm).
When you look at the average speed for each time of day (averaged over the month since fibre was finally live here), you get
The lowest of those averages is 71.4Mbps at 8pm, and the highest is 73.2Mbps at 10pm.