The phrase "just several" is correct and usable in written English.
It is used to emphasize the smallness of a number (usually fewer than 10). For example, "We have just several days before the project is due."
But they see each other just several times a year.
There's just several ways to do it, I guess".
They harvested the grassland just several days before, so the grassland seemed to be very flat.
West Park's membership has decreased to just several dozen worshipers since it closed.
Dilek Hanif, who designed them, insisted they were "just several among many other proposed models".
The number of soldiers on Kinmen has dropped to just several thousand.
It was just several months ago that Dysport™ gained FDA approval for cosmetic indications although it has been used widely in Europe for several years.
For instance just several months ago, Philips released The Slimstyle, the first "pancake-shaped" LED light bulb.
We are now able to prophesy impending cataclysms with a specificity that would have been inconceivable just several years ago.
Who listens now to The Spice Girls - a global phenomenon just several years ago?
To be honest, I didn't get around to seeing the film until just several years ago.
