Is it possible to use UK/EU lanes as a Registered Traveller the first time you enter the UK after applying?

Last time I visited the UK, it took 3 hours to get through the immigration queues.

I recall seeing signs saying something like:

"Registered Travellers from [list of countries] can use the EU/UK lines."

I have another trip the the UK in a few months, and I am really dreading the giant queue, especially after a 17 hour flight.

So I am looking up how to become a Registered Traveller.

It says:

1. Apply online for Registered Traveller membership. ...
2. You’ll get a decision on your application within 10 working days. ...
3. If your application is accepted, the next time you travel to the UK you must go through the ‘other passports’ lane and fill in a landing card.
4. The immigration officer will check that you meet the criteria and tell you if you can become a member. ...

So does this mean that being accepted at point 2, isn't a real acceptance. You get the real acceptance the first time you enter after applying, using the ‘other passports’ lane (i.e. the non-UK/EU line). And then after that if you visit the UK again (assuming all successful), you get to use the EU/UK lane?

(I mostly just want to know if I am understanding it right. I think other things mean it just isn't financially worth it to me to become a registered traveller. I'ld need to pay for a Visa since I've not visited 4 times before)