It says they can convert them over to common shares before the TWO years are over.
No stipulation as to when they are allowed to sell Them:
"The Investor may convert the principal amount of the Notes (as well as other notes it currently holds as referenced above), together with accrued but unpaid interest thereon, into Shares at the applicable conversion price, at any time or from time to time prior to maturity."
When can they sell...Immediately after Conversion..which does make sense.