To ensure Pebbles uses the litter box consistently, you need to be CONSTANTLY taking her to her box. My puppy is litter box trained, and in the beginning I was taking her to her little box every hour or so that we were awake. Don't give the puppy a chance to have accidents -- keep an eye on her at ALL times -- I doubt a spray will keep her from using the potty on the bathroom floor.
Watch her like a hawk, keep taking her to the box, and praise the heck out of her when she uses it
Also -- you've only had her a couple of days -- it might take her a while to be very steady about using it -- she's just a baby!
Watch her like a hawk, keep taking her to the box, and praise the heck out of her when she uses it