Not super unusual if your senses aren’t developed, but I have noticed with servitors, beginners tend to notice them easier than other types of spirits.
I usually tell people not to worry if they notice nothing- it’s not really a big deal as long as you put in the effort to contact them, a one way call is still a call- they can hear you.
It can be as subtle as a flash of light, the air around you feels different, or even something like if you thought you imagined seeing, hearing, smelling anything that doesn’t have an obvious explanation.
The early spiritual encounters can be really easy to dismiss as coincidental, or to not even realize they are indicative of spiritual presence.
Depends on where you got it, how it’s programmed etc. Many of mine are made and ready to go before I know where they are going, so to protect the future owners from having their servitors high jacked by random online viewers and the integrity of my work, I usually have them pre programmed as only being able to be summoned by someone I’ve personally given access to.
Others like the ones I’ve shared on the forum, can be summoned by anyone who comes across their information. Those I’ve created to an individuals specifications, also do not have any restrictions- it’s merely the ones I pre-make that have summoning restrictions.
You can task them more often, or send them to entities to be taught. Whether or not an entity is willing, is kinda hard to determine without divination if you don’t have an established relationship and can’t sense the entity in question.
I personally just task my servitors, assume they need time to learn and then give them a reasonable amount of time to complete the goal. If I don’t see results in the time like I wanted, I summon them and task them again, but usually either with something different, reworded etc.
The more you use a servitor, the better it will be able to complete your tasks, and the more likely you are to notice they came when you called, and the more likely you are to see results.
Like pretty much everything that takes practice, if you can put yourself on a somewhat consistent schedule, you’ll see progress faster- like if you dedicate to working with them three days a week or whatever fits for you.