How long will it take me to get a back walkover ?

okayy , i have cheer tryouts in 2 weeks & i know i wont be able to get a back handspring that fast so im fine w/ a back walkover . im very good a back bend kick over i can do that w/ no problem , its just when i qo to do the back walkover i get scared that im qoinq to fall like qoinq backward i feel like im to tall & im only 5'3 .. PLEASEE HELP ME W/ SOME TIPS !