There is never an actual number to determine when a couple should take their relationship to the next level. The couple should love each other which usually takes place after a few dates. Usually, people don’t fall in love with each other after the first date, but some do. Also, it depends on what you want out of the relationship.
If both sides are wanting the same thing either just physical contact or an actual relationship, both sides should communicate this to each other. Then, the number of dates that should take place before getting physical is different. Being physical should take place when both sides feel comfortable and feel that this is the right time to get physical with each other.