Subtracting exactly 1 calendar month from a task

[kanguyen]

In my project, I've setup a bunch of milestone dates (duration: 0 days)
for example - the announce date for a product, which is April 30, 2010.

I have some tasks in my project plan which require things to be done b
exactly 1 month (or 30 days) prior to the announce date. I've also se
these up as zero-duration milestones.

However, when I set up my predecessor lag times as FS or FF minus
month or 30 days, I get March 19, 2010.

Does this have to do with working time? I really just need it t
backtrack roughly a month plus or minus a day - so March 30 or 31.

Any ideas

 

[Jim Aksel]

Project counts 1 day as 1 work day which brings you back to 19 MAR 2010. You
can use elapsed days or FS-30ed (elapsed days). A word of caution, elapsed
time may cause tasks to fall on non-work days such as Saturday or Sunday.

Negative lag (lead time) is generally not a good scheduling practice as it
implies certanity for a future event. If there is only one task holding you
product announcement at 30 APR 2010... negative lag implies that all I have
to do is claim the predecessor milestone and I am guaranteed the announcement
will happen 30 days later. Not logically sound.

Instead, consider doing a forward pass on your schedule with positive lag.
Now, establish a *deadline* on the announcement task of 30 APR 2010 (or even
on the predecessor of 30 MAR 2010). If your schedule logic pushes either
date, then a red diamond appears in the indicator column to alert you to the
problem. Deadlines are entered fromteh Advanced tab of the task information
dialog box or directly into the deadline column.
--
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Jim Aksel, MVP

Check out my blog for more information:
http://www.msprojectblog.com

 

[Rob Schneider]

kanguyen,

Instead of using "d" as the units, try "ed" which is "elapsed days".

--rms

www.rmschneider.com

 

[Steve House]

Milstone are not fixed dates. Milestones are the events that mark an
important transition point in the project. The annouce date for a product
is the date you announce it - you may have a target date or a deadline date
to be sure but the milestone is not the date, it is the announcement that is
to take place. It will happen when it happens: ahead of, on, or after the
desired date. The annoucement will take place whenever all the prepratory
activities have completed so the announcement is possible. Better to plan
forward, detailing all the steps in the process with an unconstrained
milestone "Announce Product" as the last task in the chain. Set a deadline
of the required annouce date on the milestone. Now Project can actually
help you plan what you need to do to make the announcement on time and
predict if you'll be successful or not with a given workflow. If it
calculates the milestone will fall later than the deadline, you can't just
force it to fit by fixing the milestone date - you have to actually change
something in the workflow so you can get it done on-time.