Likely, it'll be 1-3 cycles before you can trust your CM sign, and your cycles are likely to be longer and stranger than normal. You don't necessarily have to wait till you have a real period, though. Just make sure you take your waking temp at the same time every morning, and you will hopefully be able to tell that you've ovulated based on that. Since you're not using the CM sign, though, you may want to wait for 4 or 5 good raised temps just to be sure. Post-ovulation is really the only way to be safe for the first few cycles. When you do finally have a normal cycle again, things should stay pretty normal.
Good for you for getting off the hormones. I really think this is a much healthier alternative, even if it takes a bit of work.