actually you just made our point for us.
We would not say yes, come today, Because we need God to come in HIS TIME< Not ours. God knows (as youjust said) when that will be.
Of course He will come in His time. The question is do you want it to be soon or not? Its about your personal preference, not about changing God's plan.
The prayer "Let your kingdom come" will not change His appointed time but it is our prayer and wish for it to be soon.
If we think in the way "not now, I have something in this world to finish, my Lord", something is wrong with our perspective.
P.S. Maybe Our Father will change His appointed time. God saw our prayers before appointing anything, before He created the universe, right? But its a different topic.