A couple 2 second squirts is plenty. Most carb cleaners are combustible. My advice is stay away from starting fluid.
The cleaning method is a short term, maybe work, band aid.
You may have other problems.
Things to consider:
Have you made any other changes?
Have you checked the plugs? I recently helped someone get a car started. The plugs were like new, but fouled with a shiny black carbon that prevented sparking. He had miss connected wires at the coil by placing choke heater on point connection. He then used a bunch of starting fluid. Not sure if they fouled from that, but never saw plugs like that in my 40 years of working on cars.
Do you have spark? Look for blue spark at plug, with plug body grounded.
Is there fuel in the carb? This is often checked by seeing if squirter sprays fuel.
Does the engine have compression?
I have heard that starting fluid will spin an engine without fuel or ignition, because it fires on compression. It can also break rings off pistons. Learned this from experienced machine shop mechanic.
A short 2 second squirt of WD40 in the carb with choke open, will run an engine about 2 seconds without fuel, if the ignition is working.