The only honest answer must be that it depends on your child and your exact circumstances.
Because not having an adult at home after school often goes with not having enough adult attention at other times.
But of course, these two things don't have to be linked at all.
If your child is at an age and stage where he himself is entirely happy to be first home, and is clearly unlikely to do anything dangerous while he is alone, it will probably be perfectly all right.
You may want to try and work out a different plan if: He is not happy about it, especially if he tends to be frightened of the dark, nervous of noises, etc.
It certainly will not be good for him to come home each day to day-mares, in which his imagination fills the house with monsters.
He will be expected to look after younger children as well as himself.
If those younger children would not be safe alone, it may not be fair to leave them with him, routinely.
He might be late: they might refuse to do what he told them, and if anything goes wrong he will feel desperately guilty.
You feel you have to put all kinds of restrictions on him to make it safe.
 Some children, for example, are forbidden to make themselves a cup of tea or coffee or to switch on the fire until and adult comes home.
In winter that is a pretty miserable prospect for a cold tired child.
He is not happy, at the moment, happy at school.
Not only can a solitary return home be a depressing prospect when a child is facing a depression day, the fact that you are not there may also mean that he never discusses his miseries with you while they are fresh in his mind.
While a lot of children are, sadly, left to fend for themselves perhaps for several hours after school, the following compromises work well for many families.
The child who is expected to do homework either stays and does it at school (which many schools allow as there is usually some staff in the building in charge of after-school activities or goes and does it at the local public library until it is time to meet you on your return.
The child comes and collects you form work (geography permitting) which may have the advantage not only of sociability but of making it clear to your work-mates when it is time for you to go.
The child comes home alone on one or two days of the week but has after-school care or dates with friends, on other days.
He goes and has dinner with a friend or neighbor and is either collected from there or leaves in time to meet you at home.
He comes home alone and you telephone him as you leave work so that he can walk to meet you.
The child comes home and leaves a note to say where he is going and is then free to play (within agreed limits) with friends, until a specified time after your return.