I think it depends on the workload of the health visitors in your area, some people seem to get them and others not. If you want a visit maybe chase it up but if you don't get contacted its probably just because they have a big workload x
I was 33 weeks when my health visitor first came to see me but she did say it’s not common practice to be seen before birth, just depends on the health visitor you get. Midwives won’t visit til after birth unless you’ve notified them that you want a home birth.