1) Say what but don't say when.
2) Say when but don't say what.
Never, ever, ever bet tempted to say something specific will happen in a bounded time range.
Flying cars are on the way! That disease you hate, a cure is coming! Next year will be a big year for other breakthroughs not mentioned here.
If you can't keep promises, and don't want to bullshit, then talk more about what the product already does.
OR
I can have many small sub-features that relate to this major feature done in 2 months, but I might know exactly which features make the cut in those 2 months.
Seems congruous to me
I agree and it's such a golden rule that no one follows or cares about even the slightest. Features and deadlines are to SE like velocities and positions are to QM.
This idea more thoroughly described here: https://news.ycombinator.com/item?id=21212087
But then again he probably uses deadlines as both carrots and whips.
Also seems makes good PR and gets people excited, even when exaggeration is accounted for.