We ALWAYS recommend people get a medical after 2 lessons, up to them if they wait but I've had a student delay 1st solo because they hadn't sorted themselves out.
The other old one is about the requirement for the Air Law exam before 1st solo. There is no legal requirement for this, so I wouldn't delay a 1st solo because it hasn't happened; again, they are encouraged to do it: shows some commitment to the total process.
TOO