The number one bit of advice I can offer? Be REALISTIC!
I cannot stress enough how important it is to be realistic when setting deadlines for yourself and especially for clients. I have a new prospect and had to fight hard to resist the urge to tell them that I’ll have a proposal for them prepared within a few days. That’s normally what I would have done--then I’d end up spending the next two days up all night working on it and stressing over it--just to meet this short deadline that I gave myself. But what’s the point in the added headache and stress?
Don’t sell yourself short--build in enough time so that you can get the work done comfortably. No need to tell your client that it will take two weeks to do something that would only take four days, for example. But if you know it will be tight to get something ready by the end of this week, for example, give yourself a couple extra days over the weekend, and say you’ll have it first thing Monday morning.
I was just drafting my response to this potential client, and I can’t tell you what a HUGE drop in stress I literally felt when I changed the line from “I can have the proposal ready for you by Friday” to “I can have the proposal ready for you by Monday the 8th.” In the working world, that’s only one business day later. In real life, that gives me the entire weekend to work on it to get it just the way I want it, and to hopefully turn this prospect into a client. I’m sure that if you took my blood pressure, there must have been a big reduction in a matter of seconds as I changed that line above. Just thinking of everything I need to accomplish this week PLUS a completed proposal....now, I’ve bought myself a few extra days, which is great!
Setting an extended deadline just so you can procrastinate isn't a great idea, of course. I admit I’ve done this several times in the past. That was (hopefully) the “old” me. The “new” me knows the value of time--as we all know, time is money. So I will still work hard on the proposal this week (reviewing the information the potential client gave me, researching related websites to come up with several options that might work for them, etc.) but just knowing that I don’t HAVE to get it fully completed this week makes all the difference in the world to my frame of mind. And hey, if I get it completed before Monday, even better! I’ll email it to them as soon as it is ready.
I think your client or potential client would be much happier to have you meet the deadline that you set for the particular project or milestone rather than be late. To make sure that you can do this, setting realistic timelines for yourself is important, in my opinion.