It is certainly presumptuous that we can prognosticate about the day or the hour, afterall, even the SON testifies that neither he, nor the angels, knows the day nor the hour...
But of that day and [that] hour knoweth no man, no, not the angels which are in heaven, neither the Son, but the Father. [Mk 13:32]
But the scripture provides a very plain admonition describing the thoughts in the heart of the evil servant:
But and if that evil servant shall say in his heart, My lord delayeth his coming;
because of this kind of heart thinking, the evil servant goes and:
And shall begin to smite [his] fellowservants, and to eat and drink with the drunken;
resulting in the evil servant being completely unaware of his Lord's return:
The lord of that servant shall come in a day when he looketh not for [him], and in an hour that he is not aware of,
and the evil servant's Lord shall bring judgement upon the evil servant in the form of"
And shall cut him asunder, and appoint [him] his portion with the hypocrites: there shall be weeping and gnashing of teeth.
So, what should our watchfulness include? Very few, if any of us, will be able to consistently say (in our hearts), that our Lord's return could be today, for 1 year, 5 years, 10 years or more.