My current billing cycle is due on 5 Dec 2025. I am going overseas next week. On 4 Dec morning, I perform the 'recharge' function on the Eight App and choose 5G plan for 14.80. Immediately received confirmation. Switch off phone and restart. Immediately get 5G connection. Today on 5 Dec, I log into Eight App and perform Recharge again. This time round, I selected my previous plan of 8 Dollarts. Immediately confirmed and say that the new plan will be active on my next billing cycle on 4 Jan 2026. Meaning I am on 5G until 3 Jan 2026.
Didn't know recharge while existing plan active can select plan.
This can be a good idea if you know roughly how much you are expecting to use.
For me I usually recharge after existing plan expire to maximize the duration.
It also allows you to used up existing roaming quota before upgrading, esp when usage is not clear.
Also consider step upgrading :
Use up $8 quota, upgrade to $11.80.
Then when $11.80 use up, upgrade to $14.80
Depending on your expected usage and destination (favours APAC), that could make more sense than directly upgrading to $14.80 or $18 plan.
Lastly since the 5G plans were introduced, some on 4G plans reported no longer getting 5G while roaming.
I don't think we have enough data points to be sure, but that is something to look out for.