I would like to add labels in some precise points of the ggplot graph, how can i do it?

Question

I built a ggplot, on the x axis I reported the dates and on the y values ​​with the following code:

ggplot() +  
  geom_line(aes(x=date,y=stat),color='blue',) + 
  geom_line(aes(x=date,y=fit),color='red',lty=5) + 
  ylab('Values') + xlab('date') + 
  scale_x_date(date_breaks = "week", date_labels = "%d %b %Y") + 
  theme_classic() + 
  theme(axis.text.x = element_text(angle = 90, vjust = 0.5,hjust=1))

I would like to add labels in some precise points of the graph, how can i do it? I would like to choose the possession within the graph and the writing