I agree in that the major benefit of GDPR for small companies is that you have to review and perhaps revise your processes accordingly.
However, the documentation still is required. You can create some of that later or just in case you're requested to do so but as soon as third parties (i.e. data processors) are involved that might not be possible anymore.
At the very least you'll be very busy for a few days because such requests by relevant authorities will come attached with a somewhat tight deadline ("Please supply these documents within 2 weeks or else ...").
