Potty training an almost 3 year old

We’re trying to potty train our girl. She turns three in October

She goes through phases of showing readiness and we got her some big girl underwear. She’s been wearing those instead of nappies unless it’s nap time or sleep time.

It’s been a couple of days and we haven’t had a successful potty session. She’s only had two accidents in the underwear but she’s obviously holding her business (1s and 2s) until she has a nappy on.

Does anybody have advice on how to proceed?

I’m feeling a bit federated and unsure if it’s time.