I wouldn't do it at all. It will put the "Oh, but you didn't let me look at this one first!" mentality in her head, should you be at a show and can't warm up over the jumps. She'll run out, refuse, etc. It's not garunteed, but it's very possible. She can size up the jump just fine on her way there :)
This was something that I struggled with, in regards to "Natural Horsemanship". I ride jumpers and have a very hot/spooky horse. My ground trainer taught me to let him check everything out, let him become brave about things on his own time. Which doesn't work out when i'm riding to the base of a nasty liverpool that he's never seen. So... now I school him at home with one or two jumps that are a bit "scary". They're all the same jumps he's seen a million times, except this time i've placed a towel over it, or a pinata under it, or i've even wrapped the poles with foil. This keeps him thinking, looking, but learning not to be reactive. The best place to school your horse over new and scary things... is at home!
I agree with Oxer. I constantly jump random things that I find around the barn to expose my gelding to things and to teach him that even if its scary he's got to go over if I tell him. Also, I think that jumping scary thing helps with trust, so they trust you enough to go over it. We jump tarps, blankets, lead ropes wrapped around poles. One time I used a broom as a ground pole and my gelding hit the brakes! He stopped so fast I landed on his neck! I could hear his brain going 'OMIGAWD WHAY IS DAT ON DA GROWND?!' Haha but we got over it and he became just that much braver to fences because he survived! :) Posted via Mobile Device
My trainer used a huge orange round traffic cone when jumping, pulled out her Christmas tree as a jump... and last week had my baby and I working on learning how to jump a tarp (my girl is extremely brave and couldn't have cared less about the tarp).
My advice is don't let her "look" at it by circling around it, if you're at home and it's BRAND new maybe let her smell it but don't give her too much time to look. Mares tend (at least all the mare's I've worked with and ridden) to get stuck in routines and when the routine is changed they get pissed doesn't matter if they're at home or a show. Just come into a jump slow and steady. Coming in at a slow even pace will give your horse ample time to look at the jump and let them jump as big as they need to get over it!
I only let very beginning green horses stop and look at a jump....and I am the one who tells him to do it. I will do this for every jump for the first week or so, as he builds up his confidence. However, once he understands the art of jumping and has learned that jumps are not going to hurt him, we go to the next step. I go back to tiny cross rails and he has to take them the first time. I stay really small on all of the jumps that he is asked to jump the first time on approach. Only when he is happy doing that do I increase the difficulty.
As he gains his confidence and courage, we will eventually come to a jump he wants to check first. These jumps will be of a size that he could walk over, so I have no problems keeping after him and not letting him turn away. I do not beat or even hit. I just nag and nag until he tries. THEN I praise him mightily. The praise is what is important, not any punishment. When he gets to this point, I expect him to try every jump he approaches. But, if I get him in wrong, I must be willing to break it off even at the very last moment. It takes a good while to build up a horse's confidence, but only seconds to break it.
I have had no problems with any horse I start this way going up to the highest jumps. I also have good success with sour horses I get for retraining. I take all of them right back to tiny crossrails and start them over from the very beginning with PRAISE. So many have been taught to be fearful because they expected brutal punishment when they failed! I hate that.
My mare's a pretty willing jumper. I just like letting her see them, but we'll stop that.
I've only done that a few times in the last few months, and she hasn't refused yet, just popped over them higher than she needed
I only let green horses look at jumps, and not every jump. I will walk them back and forth in front of a ditch for example. I never let any horse walk up to the front of the jump, stop and look at it, then turn away. If they are going to look at a jump, they must walk back and forth in front of the jump. This way they arent 'presented' to the jump but they get to see it out of both eyes.