Hundreds of people have started arriving in Perth and more are crossing into Western Australia by road after the scrapping of the state's COVID-19 hard border closure.
Eleven interstate flights are scheduled to arrive on Saturday, bringing in about 1300 people.
By mid-morning another 205 had crossed into WA from South Australia at Eucla and 97 had travelled through Kununurra from the Northern Territory.
Only people coming from NSW or Victoria will be required to self-quarantine for 14 days and have a coronavirus test on day 11.
But all travellers will be asked to complete an online declaration and will be screened, including a temperature check, when they arrive.
So far about 3000 people have applied online to return to WA since the system went live late on Friday night.
Authorities have said the new arrangements could cause delays and have asked for people to be patient as the state transitions to a controlled border arrangement.
Police Assistant Commissioner Paul Steel said the processes were necessary to allow people to return to the state but still keep COVID-19 at bay.
"Don't expect that you can just get off an aircraft and walk through," he said.
"This is the new COVID normal. This is what we are doing to keep our community safe.
"We make no apologies for that because the state expects that their authorities will be doing what they can to keep COVID out.
"We'll be as efficient and effective as we can."
Announcing the change on Friday Premier Mark McGowan said the state was "ready to take the next step forward".
"Our controlled interstate border is a cautious and safe step. It is balanced and sensible," he said.
"The time is right."
WA has been closed to the rest of the nation for seven months, including to West Australians who were denied entry for compassionate reasons.
Even as the rules are eased, police have warned anyone failing to disclose recently travelling through NSW or Victoria faces a large fine or potential imprisonment.
Mr Steel said there was an element of trust with the new arrangements.
"We have always asked people to comply with their quarantine requirements and in the main, people entering Western Australia, have done so," he said.
"However those people who disregard their quarantine requirements should expect to be dealt with in accordance with the law."
The quarantine rules for NSW and Victoria will only be removed once they go at least 28 days with no community spread, as all other jurisdictions have achieved.
Australian Associated Press