Above only works if the PC is able to process and time-stamp the received characters exact enough. The PC can't, so there are then only three working alternatives:
- the PC knows the sampling rate and steps a time variable for every sample it processes.
- the data is sent with a time stamp and the PC processes the data whenever it has time.
- the data is sent without a timestamp and the PC checks the current time and the data is presented with whatever jitter there will be.

1) requires that the PC never loses enough data to get one sample off. And the sample rate must be kept constant.

2) is most robust, and you have the bandwidth so there is no problem sending timestamps too.

3) will result in jitter. The load on the PC will affect the amount of jitter.