First rule of estimating: don't let them rush you into it. Even when they say "don't worry, just a very rough ballpark estimate, I won't hold you to it" - they will.
You can caveat all you like and say "best case scenario 4 months +- 20%, worst case 6 months +- 30%": they will write down "4 months" and there will be no going back.
I don't generally agree with the "double it and add some" game - because one of 2 things often happens. Either they've played the game before, and knock you down, and you're back where you started. Or else they'll say "blimey, that's more than twice as costly as we thought - better bin the project now!"
Another approach is to give them a draft plan that you've clearly thought about, and that's broken down to a reasonable degree. Then if you get challenged with "we need it done in half the time" you can say "OK, which of these steps would you like me to skip?". If you can justify your estimates semsibly, nobody's going to force you to cut them. By all means build in some contingency within that though: especially since you're worried you'll underestimate in your enthusiasm, which is indeed the most common newcomer mistake.
Good luck,
tl
You can caveat all you like and say "best case scenario 4 months +- 20%, worst case 6 months +- 30%": they will write down "4 months" and there will be no going back.
I don't generally agree with the "double it and add some" game - because one of 2 things often happens. Either they've played the game before, and knock you down, and you're back where you started. Or else they'll say "blimey, that's more than twice as costly as we thought - better bin the project now!"
Another approach is to give them a draft plan that you've clearly thought about, and that's broken down to a reasonable degree. Then if you get challenged with "we need it done in half the time" you can say "OK, which of these steps would you like me to skip?". If you can justify your estimates semsibly, nobody's going to force you to cut them. By all means build in some contingency within that though: especially since you're worried you'll underestimate in your enthusiasm, which is indeed the most common newcomer mistake.
Good luck,
tl
Comment