Well... it's a bit of a crap shoot.
They WERE doing really well about honouring the requested travel date. If you said you wanted it valid from January 1st it was valid from January 1st. Now, not so much. Someone today posted they requested December 20th and their visa is valid December 23-January 22. Not exactly the same (though closer than others).
And it's such a nightmare to get it corrected, you kind of have to go with what you are given.
Make the date you want CRYSTAL clear in your cover letter and on the application. Seriously, bold, highlight in yellow. Be obnoxious with it. Then hope they ECO reads it!
Do keep in mind that if you request a day 60 days in the future and they honor it - if your plans change and you want to travel earlier you won't be able to.