Here is something that also help...though your trainer probably taught you this.....

If a guy is fast and is the type who shoots his punch out with not prior movement...( No matter how slight most guy's somewhat get a bit tensed up not enough to actually notice it unless your looking but just enough if you know what to look for EG why I said look at the shoulders).Like a Roy Jones type guy who just shoots out his lead Right with no warning...

Jab the guy's shoulders...not hard no need for that just shoot it out there and tap his shoulder area....It makes the body have to sort of reset it self...after a bit you can judge body language on what he like to lead with as he resets himself....

like I said it is suttle but suttle things make the difference.....

Also try looking just a little down from the shoulders (around the area where your sides are if you put your arms down)....those muscles will flinch no matter what when throwing a punch even a lead right with no notice....

Try a few other methods on your own as well.....Remember sparring is PRACTICE........bvetter take a few shots sparring then when it counts