Does God have a bench of substitutes?

NORSK
When God asked Reinhard Bonnke to do an evangelistic campaign throughout Europe, the famous preachers asked a question:

 - Why me – you have already laid Africa on my heart?

The Lord replied:

 - You are not my first choice, but the two first options answered no!

Bonnke responded:

 - Even though I am your third choice, I promise I will make a first choice effort!

I have this story from Bonnke’s 'second in charge' for the campaign, Oliver Raper, whom I interpreted when the campaign was launched in Bergen.

Yesterday I read about how the Lord revealed himself to Ananias in a vision and told him that Saul was in prayer, and then he continued:

In a vision he has seen a man named Ananias come and place his hands on him to restore his sight.
Acts 9:12

I take for granted that the campaign “From minus to plus” (1) was not the first time that God’s first choice did not respond with a “Yes!”. 
What if Ananias had answered “No!”? 
Did God have a substitutes’ bench with several men named Ananias just in case?
I let the question stand unanswered, but for me it is a reminder to do what the Lord asks me to do.

Jesus once said: “if they keep quiet, the stones will cry out” (2). I pray that there will be no need for stones to cry out for me if I was God’s first choice.

‘Manna’ for today:

I want to be ready when the Lord asks something from me.

----------------------------------
(1) 

(2) Luke 19:40