Two normal (I'm 5ft1, so slightly shorter than normal for most people) strides for take off and two for landing, and three normal (longer for me, normal for normal people ) for each pony stride. But would use poles on the floor to double check first, because I haven't ridden a pony in a while That said, there are plenty of ponies jumping senior classes on horse distances, so unless it was a particularly short striding pony, if it's slightly long I don't think it would cause massive problems
Have a play around with canter poles to work out what a canter stride is for your pony and then you probably want about 2 small strides for take off and the same for landing
My pony likes about 4 normal/big strides but it depends on his length of stride as well
Although we might just be trotting, depends on her mood Only tiny jumps so she might not oblige a canter lol!
If she's just going to trot into/out of the jumps, just keep it as the same amount of strides I'd give her for canter, or less?