The advantage of things like Scrum is that a 1 week sprint size should flag up slippage within a week.
It's hard for people to actually know they're going to miss a deadline, and they might feel that they can course-correct. But if you have a really clear definition of done, and work broken down into pieces that fit within a week, and you do planning each week... then you will know as soon as you slip, that you are slipping. And if the product owner is involved in planning, then there's just no hiding it and he can communicate it upwards.
Things like agile and Scrum are core processes for this... they give you nowhere to hide, and that helps those who need delivery to get that feedback early so they can prioritise what they most want delivered (if the deadline is more important than the totality of the delivery) or how they're going to communicate slippage up the chain (if the totality of the delivery trumps the deadline).
If this is all noise to you, then just do this:
1. Break your 3 month project down into logical pieces of work, each one small enough for you to understand roughly how to do it (realistic work effort) where no single piece of week should be larger than 1 week (if it's bigger, it's a smell that you're estimating badly and don't understand each of the parts involved).
2. Order all of the pieces of work such that you are doing the most important things (decided by the project sponsor) first.
3. At the start of each week declare what you will finish that week, always the most important things you could be doing... and get to work.
4. On Friday, see whether you finished everything you said you would. If you have not... you have slipped and it impacts next week and gets communicated.
The advantage of things like Scrum is that a 1 week sprint size should flag up slippage within a week.
It's hard for people to actually know they're going to miss a deadline, and they might feel that they can course-correct. But if you have a really clear definition of done, and work broken down into pieces that fit within a week, and you do planning each week... then you will know as soon as you slip, that you are slipping. And if the product owner is involved in planning, then there's just no hiding it and he can communicate it upwards.
Things like agile and Scrum are core processes for this... they give you nowhere to hide, and that helps those who need delivery to get that feedback early so they can prioritise what they most want delivered (if the deadline is more important than the totality of the delivery) or how they're going to communicate slippage up the chain (if the totality of the delivery trumps the deadline).
If this is all noise to you, then just do this:
1. Break your 3 month project down into logical pieces of work, each one small enough for you to understand roughly how to do it (realistic work effort) where no single piece of week should be larger than 1 week (if it's bigger, it's a smell that you're estimating badly and don't understand each of the parts involved).
2. Order all of the pieces of work such that you are doing the most important things (decided by the project sponsor) first.
3. At the start of each week declare what you will finish that week, always the most important things you could be doing... and get to work.
4. On Friday, see whether you finished everything you said you would. If you have not... you have slipped and it impacts next week and gets communicated.