A pilot telling us their a/c type during their first contact wastes hardly any time whatsoever. What does waste RT time is pilots not listening to the ATIS correctly subsequently omitting their a/c type on first contact with Heathrow and then we have to go back to them to ask them to report their a/c type.
This isn't something that bothers me particularly, what however annoys me enormously is a/c checking in with their callsign only or speed only with intermediate director on 119.725 and 134.975. Callsign only is for final director on 120.4! Isn't how to check in something that pilots get taught at an early stage, it just seems incredibly unprofessional!
Getting back to the original point though, its safety critical that we get the a/c type correct. Similarly why we get a/c to report their cleared level; we can't trust the fact that because your Mode S SFL is accurate that that's the level you'll stop at, we need you to tell us too. It's about limiting risk, and when I was training I was told 'if it can go wrong it will go wrong.' It takes no time at all to include your type on first contact, just remember!