Holidaymakers travelling through the “extremely busy” Port of Dover may face “bottlenecks” of traffic, bosses there said.
The processing time at the border is 90 minutes, which is the time expected for peak travel days, an update from the Kent port said on Wednesday morning.
All the positions for French border officials, Police Aux Frontieres, are open, it is understood.
A Port of Dover spokesperson said: “The port is extremely busy due to high volumes of passengers arriving too early for their sailing, causing bottlenecks.
“Please keep to main routes (A2/A20) and do not arrive more than three hours before your sailing.”
The Kent port has been preparing for summer holiday getaway traffic, with measures put in place to minimise queues.
Bosses are urging car passengers embarking on summer getaways to arrive up to but not more than three hours before their booked sailing.
This is up from two hours last year, while before the end of the Brexit transition period the port gave no advice for when people should turn up.
Port bosses said anyone who misses their sailing will be put on the next available trip.
Expected car arrivals were expected to peak at more than 2,000 on Wednesday morning and nearly 3,000 on Saturday.
As of 9.25am, car numbers totalled 1,836.
