As mentioned in another thread, you might want to look at the plan backwards
from curiosity to see what the latest possible date is that you might be
able to start but most of us strongly recommend you do the actual planning
from the earliest realistic expected start date forward. If you plan from
the finish backwards it places every task as late as it possibly can. That
means they are all critical tasks and if anything goes wrong with any one of
them and it's delayed (and something ALWAYS goes wrong with at least one
task) you're either going to miss your required completion date or have to
do a lot of very expensive - in terms of overtime costs and exhausted
resources - last minute scrambling to make it. Planning from start forward
gives you much more leeway.
Do NOT use constraints as a substitute for deadlines. Must Finish On
constraints mean that the schedule will always show them occuring on that
date without regard for whether it's even physically possible for them to do
so. Consider the simple example: We have a task that we've been given a
finish deadline of the first of June, it takes 3 days to do and it takes 5
days for the parts to get here. We put those in the schedule with the
Project starting Monday 23 May 8am, Parts Delivery 5 days linked to Do
Assembly 3 days and Do Assembly has a MFO constraint of 5pm 01 June. So far
so good. Now first thing tomorrow morning when we call the parts vendor he
tells us that the parts are backordered and won't be delivered for 10 days.
So we change the duration of Deliver Parts to 10 days. But guess where the
schedule now shows the Do Assembly task? It still sits right smack dab on
top of June 01, it hasn't moved because the constraint says it CAN'T move.
Depending on our preferences for message we may or may not get a message
alerting us but one thing is certain, with the parts now not even getting
here until the 3rd of June there's not a snowball's chance in hell that
assembly task is going to actually finish on the 1st of June even though
that's what our schedule promises - it's physically impossible for it to
even start before the 6th and our schedule is misleading us about what
can/will actually happen. I suggest we use Project to help us avoid such
problems and it best does so when it freely shows us what we're GOING to get
rather than what we WANT to get. Constraints used as you seem to be doing
force it to lie to us, promising we're going to get what we want whether we
can have it or not.
