It was hailed as a fresh era for rail travel in the region, but no dates have been set for when Greater Anglia's new trains will be running on its main line.
The rail operator is replacing its existing fleet with 169 new trains, giving passengers more seats, air conditioning, plug and USB charging points and easier access for disabled people.
They were introduced on the Norwich and Lowestoft line in July this year and the Norwich to Cambridge route the following month.
Greater Anglia said at the time that it planned to roll out the majority of the new trains on regional lines, called bi-mode, by the end of 2019.
It also said in July the new intercity trains would start running between Norwich and London later this year, but it is still not known when.
On Twitter, a customer queried when the Norwich to London line would see the new trains, to which Greater Anglia replied: "Unfortunately we don't have a date yet."
A spokesman confirmed that while there was not a date for every line on the network, "every train in our fleet will be replaced with a brand new one by the end of 2020".
She added: "It's a phased introduction and many of the new trains are still being built and tested."
Greater Anglia said it is carrying out "rigorous safety and performance tests" on the new trains, adding: "Later this year, we will start to bring our new longer electric intercity trains into passenger service on the Norwich-London route and we'll continue to roll out our new bi-mode trains, which are powered by electricity and diesel, on other routes on our network."
The company is getting 20 electric trains from Stadler and ten of those will be for the intercity route between Norwich and London Liverpool Street.
The Norwich to Sheringham line, meanwhile, will get new trains this autumn.
Testing is also under way from Ipswich to Cambridge and Peterborough.
Each new train has to run 2,000 miles across the region before it can enter passenger service.
According to figures released last week by the government's Office of Road and Rail, 66.6pc of Greater Anglia trains ran on time from April to June, which was above the national average of 64.7pc.
The train company came fifth in the national league table for improved punctuality, with the number of cancelled trains decreasing slightly from 2.5pc to 2.4pc between April and June.
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