It is pretty clear that the first 25 % of the POET shares the former DenseLight owners received will get free for trading on November 11th.

From the shelf prospectus:

• On May 11, 2016, the Corporation acquired all the issued and outstanding voting securities of DenseLight Semiconductors Pte. Ltd. ("DenseLight"), …

From the 2016-04-28 news release:

• All management shareholders of DenseLight shall agree not to sell, transfer, pledge or otherwise dispose of the POET Shares for a period of six months, at which time such shareholders may each sell up to 25% of the POET Shares received by them. Management Shareholders may sell an additional 25% of the POET Shares received by them after twelve months. Thereafter, all management shareholders shall be able to sell the remaining shares after 24 months from Closing.
• All non-management shareholders of DenseLight shall agree not to sell, transfer, pledge or otherwise dispose of the POET Shares received by them for six months, at which time such shareholders may sell up to 25% of the POET Shares received by them. Thereafter, such non-management shareholders may sell the remaining shares after 12 months from Closing.

Highlighting in the above quotes is mine. I also introduced a paragraph in the second quote to more clearly differentiate between management shareholders and non-management shareholders of DenseLight.

Anyway, 25% of the POET shares will become free for trading six months after closing – and that's November 11th. You can find this date and the other two dates in my POET Technologies Timeline, which I just refined for the above mentioned differentiation.