It will take much more than days of weeks, your poor bird will now have to cope with being alone for the first time in his life, not something which you can cope with in a week.

He will get used to it, now because he is alone you will have to spend more time with him and give him more company. Have you tried leaving the radio on when you leave i find that helps also giving more toys or leafy greens like kale to give him something 'exciting' to do when you are gone.

i had 3 cockatiel but with stuff happening around the house i had to get rid of 2. its been a week with him but every time i leave the room he always goes back and forth in his cage and chirp to get my attention. i have to ask, is there anyway to make my bird more calm when i leave the room or when i leave the house for a few days?