Starting Graph After Value of 100

Is this what you mean?

library(tidyverse)
library(lubridate)

url <- "https://opendata.ecdc.europa.eu/covid19/casedistribution/csv"
sample_df <- read.csv(url)

sample_df %>%
    mutate(dateRep = dmy(dateRep)) %>% 
    filter(countriesAndTerritories %in% c("Canada", "United_States_of_America", "Iran", "Italy")) %>%
    arrange(countriesAndTerritories, dateRep) %>% 
    group_by(countriesAndTerritories) %>% 
    mutate(cum_deaths = cumsum(deaths)) %>% 
    filter(cum_deaths >= 100) %>% 
    ggplot(aes(dateRep, cases, colour = countriesAndTerritories)) +
    geom_point() +
    geom_smooth()

Created on 2020-03-26 by the reprex package (v0.3.0.9001)

If this is not what you mean, please provide a proper REPRoducible EXample (reprex) illustrating your issue.