This is an example table with 2 x Nitro+ 470 4GBs mining at 29.65 MH/s
each at full speed, i.e. 59.30 MH/s total, having 4078MB of DAG buffer
space available. Power draw will stay roughly the same, so your
efficiency will take about the same hit as the hashrate.

Epoch  DAG MB  DAG %    Hashrate  Loss %  ~date (https://minerstat.com/dag-size-calculator)
381    4072    100.00%  59.30       0.0%  10th Dec 2020
382    4080    99.95%   58.38      -1.6%  14th Dec 2020
383    4088    99.76%   54.89      -7.4%  18th Dec 2020
384    4096    99.56%   51.46     -13.2%  21st Dec 2020
385    4104    99.37%   48.29     -18.6%  25th Dec 2020
386    4112    99.17%   45.17     -23.8%  29th Dec 2020
387    4120    98.98%   42.17     -28.9%  2nd Jan 2021 
388    4128    98.79%   39.35     -33.6%  5th Jan 2021
389    4136    98.60%   36.80     -37.9%  9th Jan 2021
390    4144    98.41%   34.23     -42.3%  13th Jan 2021
395    4184    97.47%   22.46     -62.1%  16th Jan 2021
400    4224    96.54%   12.55     -78.8%  20th Jan 2021