I’ve used Airalo esims twice in recent months - generally they were easy to use. The app gives good information about how much data you’ve used so you can keep track.
The first time I actually activated he esim while in the UK which meant that the timer started immediately. However as it was valid for 24 hours more than I needed it wasn’t a problem. The second time I opted to wait until I arrived abroad to activate but I appeared to need Wi-Fi access to do that so I regretted not having done the activation in the UK!
I presume your phone is compatible - my husband’s old iPhone was too ancient to use them.
One word of caution - my first esim was nearly exhausted within 24 hours as I had pretty much all apps set to use mobile data, including photos, music etc. I quickly switched everything off from mobile data and just switched back on selective apps as needed.