when she is not ovulating which is very hard to tell.
but ovulating or not she can still get pregnant easily.
So there is no best time.
if you want to try it without condoms, then do it, BUT be careful that you do not bust inside of her.
Of course this method is not always safe.
pre-c.u.m does not have sperm so do not worry about that.
Just dont bust inside or in d middle or almost in the exit of her vagina because the sperms can swim.
have a napkin/towel ready to clean up your c.u.m, or take a shower together afterwards.