Is there any evidence in Act 4,Scene Two that Macduff's son was killed during the daytime?
Yes. Rosse says "Things at the worst will cease, or else climb upward /To what they were before" (ll. 24-5), alluding to the sun that sets and rises again. In Macbeth, the sun always rises up again, except for Macbeth and his lady, who have disturbed this natural order of things, the Great Chain of Being that hierarchically structures the cosmos and keeps planets in their places.
This is why night and day metaphors abound in the play.
The whole play toys with concepts of light and darkness, day and night. In act 2, scene 4, Rosse talks to the old man and tells him: "By th' clock ’tis day, / And yet dark night strangles the travelling lamp". (ll.6-7) Even though the clock claims it is still daytime, the day is eclipsed by an unnatural darkness because of the unnatural crime Macbeth has committed in the murder of King Duncan. Interestingly, in the 1948 movie version, it is Lady Macduff who speaks those lines, not Rosse.
Also, Lady Macduff and Lady Macbeth are constructed as complimentary characters, one dedicated to life and nurturing, the other to death and destruction. As Lady Macbeth's last scene is one that takes place in darkness after the sleepwalking scene, it is natural for Lady Macduff's final scene to take place during the day, as she represents light and goodness.