Short answer: 6 months (recommended)
Long answer: Grief is the unique pain that follows the loss of a loved one. It can take the form of physical, emotional, and cognitive symptoms. If your pain follows the 5 Stages of Grief, you would have experienced denial, anger, bargaining, depression, and acceptance. Your mind and your body are both processing this overload of emotion. The grieving process can take 1–2 years, but your first couple of months are your most vulnerable.
Our image of 19th Century Spiritualism — a round table, crystal ball in the center, rapping beneath the table — came about after the 1918–1920 influenza pandemic and the end of the first world war in 1918. The worldwide death toll of World War I was estimated at 20 million and the victims of the pandemic were at least 50 million. Up to this point, survivors of both events had never seen death at this scale.
Worldwide grief and the impaired judgment that comes with it meant that the landscape was ripe for phonies. The people needed comfort and answers from the universe. Seances became trendy. Mediumistic materializations like ectoplasm vomit that suspiciously resembles white cloths became a norm. Floating musical instruments and pale apparitions in the corner conveniently dark rooms also followed.
The grieving accepted these bizarre performances because they were still reeling from sudden and massive. They were desperate to connect with their husbands, children, parents, etc. If the whole world could suddenly turn on itself and a mysterious illness could wipe out millions of people, why couldn’t the dead materialize as ectoplasm, right?
To be clear, I am a student of the occult and do believe that it’s possible to contact the dead, but a true connection is too subtle to require the appearance of an ethereal body. Also, let’s not forget that scammers will always seek people with weak spots. When you’ve experienced loss, the pain can be so raw, that your entire being becomes a weak spot.
Six months typically marks an improvement of emotions in the grieving process, which means better decision-making. This is why mediums tend to suggest that clients wait at least six months before attempting to contact someone who has passed. Let’s be clear, these six months aren’t for the dead, they’re for the living. The dead have a different concept of time. Whether you wait a week or six months, it doesn’t matter to them. But you should be in a decent headspace when you attempt to contact the dead. Otherwise, you might become a victim to a cold-reading fraudster. It’s also more likely that you will leave a reading feeling at peace yourself.