When can one apply for BVB if they apply for onshore spouse visa when in tourist visa

I am a PR since the last one year. My wife is in Australia in a tourist visa and is an Indian national. She has another 2.5 months for her 3 months stay condition to expire. Other than that, she has a multiple entry tourist visa that expires next November. She doesn't have conditions like "No further stay" on her visa.

I wanted to apply spouse visa for her now when she is onshore, but she has plans to go to India for 3 months starting January, to complete her studies. After coming back in April end, she might need to travel again in June for 3 months. I learnt that she needs a bridging visa B to travel outside the country. If I apply for spouse visa today, when can she apply for BVB as her tourist visa is currently valid?

Will applying for BVB trouble her spouse visa applicaiton? Some people suggested me to apply for spouse visa after she comes to Australia permanently. With the changing rules, I was of the opinion not to postpone the visa application. Given my scenario, what would be the best option? Should she apply for the PR spouse visa now and expect a bridging visa B every time she travels back to India or apply after she comes in permanently later next year?