When bringing bringing home a new budgie, it's advisable to follow quarantine practices. The new bird should be in a different cage and room away from your other budgie. This is done as preventative measure so that a potential illness carried by the new bird doesn't spread to your other bird.
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If you have recently gotten your first budgie and are yet getting to know your budgie and working on establishing a bond with him, it would be best to hold off on getting him a new friend as this would only make the work put into taming more challenging and the chances of you to develop a stronger bond with your budgie will also be reduced.
For now, you can take the time in being more acquainted with your current budgie's personality and temperament (to see if he would take well a potential same species friend in the future) and to give the chance of forming a stronger and more solid bond with him. By doing so, while the dynamics would change when introducing a potential new budgie, most of the work you have put into taming and forming a trusting bond would not suffer such radical changes, especially when the continued work in bonding and spending daily time with the budgie is done.
If you want to move your budgie to a different cage, you can place both cages close together with the doors open and facing each other.
Placing a spray of millet on the new cage may encourage your budgie to move there.
Before doing this, it's best that the new cage is fully ready with the perches, toys, food/water containers and remaining accessories.