How long does it take to see an oncologist?

I would suggest to your friend that waiting for a referral just might not happen. The doctor who ordered the tests may recommend someone, but ultimately it's your friend's choice.

Start reviewing the bios of oncologists at the primary hospital where she receives treatment. Ask about oncology centers, staffing, whether or not music therapy is included, whether or not there are activities for patients and/or their families. Visit them as well.

The infusion center where my sister received cancer and radiation was beautiful, conveniently situated in an area bordered by a marsh from which resident geese occasionally came up to explore, and honk. I could see them from the magnificent atrium, open to the sun, which flooded the area with soothing warm rays.

A Reiki therapist also visited, weekly I believe. My sister found that very soothing in the last months of her life.

This center had art and ceramics groups, needlework displays, and what they called "boot camps" for the patients and their families.

Do some online research about the best oncologists in the area; call and ask if they're taking new patients and the waiting time for an appointment.

I totally agree with others; this is not a condition in which waiting for a referral is appropriate. If you find an oncologist in the same hospital, it's likely that the tests and Dxes would be available electronically to physicians at that hospital.

You might also contact a local Gilda's Club and find out what therapeutic activities are available for your friend, her friends and her family. The local GC here had specific subgroups for various kinds of cancers. You might even meet someone with a similar condition who has an oncologist to recommend.

In the meantime, the family can learn a lot about the whole spectrum of cancer treatment through the CURE magazine, available for free to those with cancer and their caregivers, and also available online.

Many insuers allow a patient to request an appointment with a specialist without a referral but if this is not the case request one immediately.
Aside from that you have not given enough details for people to be able give better advice.
These days due to the many cut backs in funding it is not unusual to wait months for an appointment. In this case it is urgent.

Primary probably ordered tests so an oncologist had at least results to consider the diagnosis. Does her insurance require a formal referral? If so, she needs to request that from her doc.

Sutter Health has a cancer center
Check their website and see how a patient can be seen for an opinion

In your friend's shoes, if she has been told by her primary that she has lymphoma, or that s/he suspects lymphoma, I would be looking for an oncologist, not waiting to be given a name. Or maybe call one Cancer Centers of Amerca?

Lymphoma is cancer of the lymphatic system.

What is wrapped around her aorta?

Who told her she has lymphoma?