I'm wondering why you don't just have sex the traditional way? That would be my suggestion. Sex every other day from day 10 of her cycle to day 20. good luck
A woman could certainly get pregnant by this method. If you do this about every third day from the end of her period to the beginning of her next period (if it comes), it should produce a good chance for pregnancy. Her masturbating does not harm the prospect of getting pregnant, in fact, when she orgasms her uterus contracts, and that might help sperm move up and in. Why do you begin by masturbating if you are going to end in your wife's vagina? It seems you could skip a step and simply insert your penis after some foreplay when her body feels ready.