option convert date

long on oppies long on ideas short on facts about sums up my wte position...
im not that savy with the option routine but should have bought toxo rather than tox so when wte came on the radar i went the oppie way
i did see mfs sit pat in the middle of the year to kill the options and since has doubled.
i cant work out what forces are at play here but am tending to think as it is in the right sector (if gold doesnt tank) that it will rise in january there has been too much good news not to have it over the mark.
can anyone advise as to when the money has to be paid to convert is it before 31/12 or after that date
thanks in advance and sorry for making you read my tail of woe.