ac light blinks on startup with squeling for a bit

It sounds like your belt is slipping, could be an old hard belt, loose belt or bad bearing or internals on compressor not allowing good belt to turn the compressor. The computer wants to see a good turning compressor or the computer will turn off the compressor and start to flash the light on the console, have seen broken speed sensor inside of compressor be a problem also.

If the engine is warmed up, also meaning the compressor is warmer due to heat from the engine bay, will the compressor work every time once warmed up a bit? If you turn off the AC when you stop driving with vehicle, start it up later or the next day and allow it to warm up some, then try to use the AC, does it squeal after warmed up first?