I would also suggest renting. Expectantly when you are first starting out. You can budget the rental fees as an expense when billing clients. I have actual heard of some pros who only own the 16-35 L ii, 24-70 L ii, 50 f1.4, and 70-200 L. They may may also own a 100mm macro of the 35mm L but make most of their living off of the 2.8 zooms. All other lens are rented on a per job basis. Make sure to set aside a percentage of your earnings for needed gear to buy what you can use now.
Personally if you are considering both video and stills the lack of IS on the 16-35 and the 24-70 may be a deal breaker. The Tamron 24-70 may be a better option in this case. So you should really rent both before considering a purchase. 2.8 is not really fast enough on a crop for indoor use with out IS. Consider a flash if you do not have one.
I went the buy full frame lens rout when still on crop and bought the Tamron 28-75 right after buying my first rebel. I was not real interested in wide angle at the time. In the end I bought the Canon 15-85 for reach and IS a year later after buying a 60D. I had fallen down and messed up my Tamron. I actually used that as an excuse to justify the purchase of the 15-85mm. I had the Tamron 28-75 repaired and it is still a fantastic lens. (In fact it is now an exceptional copy of the lens after repair.)
Now I think it is a requirement if you own a crop camera to by a wide angle lens made for a crop. It does not matter which ultra wide crop lens you buy but keep in mind the Canon 11-22 holds its value and the Tokina 11-16 is optically the best. In reality there is not much difference in 22 and 24 on crop is it is possible to make do with a Crop ultra wide zoom and a 24-70mm zooms. I would consider buying the Sigma 18-35mm if I had not bought a 6D. The range would cover 50-65% of my indoor shooting needs.
You may also reconsider your order of purchase. I knew a photographer who freelanced on the side that still had not bought a wide angle for his Full frame camera. At the time he had bought 3 copies of the 16-35 L I and returned them two copies of the 17-40 and returned them and rented the new 16-35 L II twice. In the end it did not make sense for him to switch out the 7D/Tokina 11-16mm for wide angle use. He had a full set of 77mm filters that would have to be upgraded and could not justify the expense of another full frame camera at the time. He did have a 24-70mm and a 70-200mm lenses and considered them essential. The uses his photo earnings to pay for his photography hobby. So a camera/lens has to pay for its self in his mind.
This type of mindset if very important for a freelancer because if you do not think of your gear this way you are not a freelancer. You have photography as a hobby.
6D, 60D, Rebel XS, EF-S 15-85, EF 70-200f4L, EF 100f2.8L, Tamron 70-300VC, Tamron 28-75f2.8, Tamron 150-600, EF 40f2.8, EF 50f1.8, EF 85f1.8, EF 24mmf2.8IS EOS M 22f2, 18-55, EOS M-EF adapter, Nex6, SEL50f18, SEL1018, DN 30f2.8, adpaters and Fd and M42 lens.