Now we're getting somewhere. So, instead of asking, "should I wait for 4G?", I shall ask for a speed comparison 3G/4G.
Even a cracked record is right twice a day ... or something like that.
3G maxes out real-world at about 1Mbps. 4G averages 5Mbps and can burst to 10Mbps, real-world. 4GLTE does about 8-10Mbps, with bursts to 20Mbps.
As far as waiting for 4G, I'd say following the same philosophy as modems a decade ago: use external technology until the tech matures to its maximum speed. It was easier to by a 14.4k, 28.8k, 33.6k, then 56k modem than to keep replacing your laptop every time a faster model was released.
I think 4GLTE will be the max, so once that's rolled out where you plan to use the equipment, that's the time to get it installed rather than use a hotspot or tether.