Contrary to your running and cycling training, swim speed work during the early season should be kept at a minimum until you've spent a solid block of time focusing on technique and pacing.
By adding speed work, or more accurately threshold work into your training now, you can improve your ability to pace yourself more efficiently. Here are some tips on how to do it.
By adding speedwork into your training now, you can improve race-specific speed, mental acuity, running form and cadence. Here are some tips for how to do it smartly and effectively.