In outline, you would take two data frames, with real vs. synthetic and do something along the following lines
p <- ggplot(real,aes(Time,estimate) +
geom_line() +
geom_line(synth,aes(Time,estimate) +
geom_vline(xintercept = 2012)
Probably the challenge will be converting Time to a proper datetime object if it isn't already. After that it's mainly a matter of decoration and labeling.
Give it a shot and come back with a reprex with data frames skinnied down to just the two columns for each of real and synth. You can get those by copying the output of unparse(real) and unparse(synth)