Netgear CM3000 Modem not showing increased upload speed

I purchased the CM3000 to get an increase in my upload speed, but there's been no change in my upload speed yet.  How long will it take?  I'm on the x2 Gigabit plan with 2GBps Down / "up to 300 Mbps upload", but the upload hasn't increased above 70, which is where it was before I got the modem.