Covid vaccination. Before 3 months?

Nothing is going to happen, efficacy of the vaccination might be reduced. Vaccination is supposed to be taken three months following recovery.  If vaccination is done prior to this period, the effectiveness of the vaccine will be reduced owing to the cross reaction of the vaccine components with existing antibodies. Hence the time period is advised.

The most common side effects following COVID-19 vaccines are fatigue, a fever, headaches, body aches, chills, nausea, diarrhea, and pain at the site of injection, according to the World Health Organization. These may last from a few days to a week and are mostly self limiting. Take medication as prescribed by your doctor and rest. You can keep a clean wet cloth on the affected area to reduce pain. Consult your doctor if redness, tenderness, or swelling of the hand worsens. Drink plenty of fluids to stay hydrated. Avoid doing strenuous activities for at least 3-4 days after getting the vaccine. It is safer to avoid alcohol and smoking for a few days. The vaccine does not fully prevent infection by the COVID-19 virus. However it drastically reduces the chances of severe life threatening consequences and death due to COVID-19.

As per guidelines 3 months.