Questions: Family & Friends

My good friend and I are moving into an apartment together in a few days! We're both excited as it should be a good fit. Of course there's the dreaded bedroom decision. The master bedroom is larger in size (about 15ft x 10ft). The 2nd bedroom is about 10ft x 10ft and has a larger closet. I'm not sure how to bring up the conversation as I don't want to lead into any sort of disagreement right off the bat, even though we're both agreeable people.

I believe I should get the master because 1. I'm moving in first, 2. I will be there 100% of the time, 3. I work from home 3/5 days per week and would be able to set up a desk area for myself, 4. Im paying the first months rent alone since she's leaving to Europe for 2 weeks and won't be moving in until her old lease is up in July, and I am also the primary resident on the lease, I found and viewed the apartment, I paid and initiated the applications and had to make sure she stayed on top of what she needed to send in and pay for.

I think she wants the master because she has a king bed and she also has a 7 year old son. BUT her son primarily lives with his dad. She usually visits him where they live a few hours away, but occasionally she'll bring him up for a weekend during his school breaks. I told her if she decides to bring him up more often, i am more than happy to watch him while she works. She also has a long distance boyfriend who visits rarely as he's from the UK (we're in the US) and I won't really have visitors. She is looking for a remote or hybrid job also, but she currently works at a bar.

I think the decision is obvious, in my favor. However, the conversation hasn't come up yet and I just don't want to create any bad blood. I even offered before to pay more of the rent since she wouldn't be there as often but she refused and said we'd split it 50/50, after the first month.

How do you think this should be brought up and who do you think should get the master?