I, and many others, believe you can give a general time frame using Tarot cards, how readers do this can vary depending on their personal preference. Truthfully though, predicting a completely accurate time is not really possible. This is because of so many variables that can go against the timing of the outcome, including the actions of the person you read for once the reading is done. However, here are some ideas and examples of how you might be able to determine a general time or date.
Take for instance; the Major Arcana cards can sometimes be associated with a Zodiac. If one of these is drawn it could be used to determine a time frame based off the Zodiac it represents. They are also sometimes used in association with certain days of the week.
Some readers will assign the suits of the Minor Arcana to time measurements, but again these will sometimes vary depending on who is doing the reading.
Cups Months or Autumn
Pentacles Years or Winter
Swords Weeks or Spring
Wands Days or Summer
So take for instance that you draw the 9 of Cups, you may interpret this to mean that the event is going to happen nine months from now, or within the next nine months.
Still others simply choose associations for their cards on their own, that could be nothing like the above. This method is to simply have some kind of reference when someone asks for a time, or date.
Most readers however will simply go on their own intuition for the reading as a whole. This is probably the best and most accurate way of determining a time frame. Perhaps a certain card keeps drawing your attention (say the 3 of Swords), and the reading as a whole has a number of influences from the moon. You may take this to mean that the event(s) will happen within the next three months.
You can also do spreads and readings that are specific for a certain time frame. Such as a spread/reading that will only look at events for the upcoming year, month, week, or even day.
In the end it really is something you would need to work out for yourself. Trust your own instincts and intuition. :)
Peace be with you,