Are you preparing a letter of explanation for other reasons? I highly (highly!) doubt that IRCC is going to verify specific dates like this in 2010. But if you are very worried about this - or if you are otherwise preparing a letter of explanation - then yes, write a sentence about this.
Otherwise, just put your estimated dates as above.
Thank you so much for the inputs . Appreciate!!
Yes, I am putting in LOE for certain other things too. I had gotten WES only for Masters degree in US, but I am declaring an experience prior to Masters too. Does it mean I should attach the degree and transcripts for Bachelor's in LOE or not needed at all.