Two months before the 2011 AV referendum the polls were pointing to a YES victory
QSaw 
NO2AV won by 35.8%
The table shows the published AV referendum polls for February/early March in 2011 about two months before the election in early May. As can be seen  all the online polls had leads for the YES camp. The only phone poll, ICM, had it level-pegging.
Unlike the EU Referendum there was much less interest and awareness and, of course, these  were carried out before the Cameron-approved anti-Clegg attack adds that dominated the final period.
But the message is still there – polling this far out from June 23rd  might not be a good guide to the eventual outcome.
It is repeatedly and correctly observed that the history of referendums in the UK suggests that the status quo is the normal result. But will that be the same here?
Cameron is taking such a front line role that the vote could end up as a referendum on him. Equally it could also be a referendum on any one of Farage, Gove, or Johnson.
Whatever we know from past actions that Cameron can be totally ruthless when he turns his mind to it.