Is now a good time to think about a fixed rate for our investment loan?

Hi John,
Impossible to say what will happen with interest rates. The choice and the decision lies with what you feel comfortable with.
Most experts expect that it is more likely that the next move will be 0.25% up, possibly within a year and then another within 18 months.
Banks and other lenders can, have and will continue to change rates according to their own funding and cost structures as well.
If you have surplus income and a strong cash buffer you may take the risk and stay variable, whereas if cash is tight and a small increase would make things difficult for you, it may make sense to fix some or all of your loan.
Only hindsight will tell us what was the correct choice, so speak with your broker or an adviser and do what makes you sleep best at night
Best regards
Scott