Yes, but everyone wants an idea of when projects will be done. It's not very often people will accept no timescales at all. Clients also want to know the costs before the project too, so you have to come up with some time estimates even at the quoting stage.Offtopic now, but try not giving a deadline at all. Or to be more useful, have set deadlines before you've decided what work will be done, on a regular date (fortnightly or monthly works best) then instead of saying when everything will be done, tell them you'll have "x" amount done. No point lying to make you look good, it'll bite you in the bum when you fail.
Coming up with half way accurate estimates is a job in itself, it takes a long time before you start to get an idea of how long a job will take you. Often you're still wrong but the trick is to make sure you over-estimate.