In Matthew 12:13, Jesus tells the man "Stretch out your hand" and the man stretched it out and the hand was completely restored and as sound as the other one...
What if the man with the shriveled hand didn't obey and decided not to stretch out his hand, he will not have been healed. What if he delayed? he also may have not been healed.
When God tells you something and you obey immediately, you see and witness His power there and then powerfully.
Take this and meditate, think about it, apply it, and remember those times that we have all failed to obey immediately, and now knowing this, strive not to delay when you obey next time.