Does 现在 make 就 redundant in "你现在就去做。"?
就 in 你现在就去做 functions as the adverb "just". 


你现在去做 = you go do it now

你现在(就)去做 = you (just) go do it now


  Example of 就 = at once; right away:


吃完飯去 = go after finish dinner

吃完飯(就)去 = go (right away) after finish dinner

吃完飯 is the requirement. Once this requirement is met, then 去 occur at once

完成工作付工資 = when you finished work, I will pay your service fee 

完成工作(就)付工資 = when you finished work, I will pay your service fee (right away)

完成工作 is the requirement . Once this requirement is met, then 付工資 occur at once

Since 你现在就去做 doesn't include a requirement, 就 doesn't carry the meaning of 'at once; right away'

If it was 你等到明天就去做 (you go do it at once when tomorrow comes); 等到明天(wait till tomorrow arrives) would be the requirement.