Pick the day that is heavy enough to wear a tampon.
Clomid can be taken day 3-7, 4-8, or 5-9. Therefore, even if the heaviest day is day 2 or 3 rather than day 1, you are not missing the boat since there is a bit of wiggle room.
Regarding the use of clomid, if clomid is going to work, it is most likely to do so withing the first three months of trying. If you are not pregnant after 1 or 2 more tries max, I would recommend seeing an infertility specialist.
Being Canadian myself (although now in sunny Florida) from Kenora ON, I know about waiting times in Canada. Not sure how long the wait is to see the infertility group in Saskatoon, but you might want to look into that and if the wait is long make an appointment sooner rather than later.