You shoulkd def dash before 4~fan, I found recently that if I buffer the dash thats when I mess it up. Just waith for her to land from the NJP first before dashing and wait for the opp char to fall a lil and then 4~fan. If you hit them high enough you can 4 lift without moving everytime.
If you really want you can just replace 4~fan lift with dash up 2~fan lift. whether you catch the 4~fan high or low it will hit everytime. U only lose 2% from the combo as whole if you do this.
As for her best jip? Id say if you know its gonna hit yes. However if your just making her jip, use f4,1 or 2,1 off a jip to hit confirm into a f2(or 4)~fan lift or a a straight fan lift respectively (if you dont wanna use meter). These are better cause then u can block conifrm into a cutter or just push back if they dont hit for better block strings.
The two combos if they hit off a jip (meterless) would be:
jip, 2,1~fan lift, dash (then space yourself), b2~af, ff, fan, ff, 4~cutter (forget how much damage, think about 38%)
jip, f4, 1, f2 (or 4 for extra 1%)~fan lift, ff, ff, b2~af, ff, 4~cutter 41-43%
Hope this helped.