I would have taken him to the vet under those circumstances. Blockage is hard to distinguish from UTI at first. it is only later when it becomes more serious, and you wouldn't want to wait that long.

If he dribbles urine he is probably not blocked, at least not totally. But many attempts to use the box in a short span of time is a warning sign. Also standing in "the position" for a lengthy time waiting for something to happen is a warning sign.

Urinary blockages are LIFE-threatening, so never feel silly bringing your cat for help.