I'll try to answer your questions, Sorry if it doesn't satisfy you

Once you got recruited (the process which i skipped), you will be dressed in red clothing and a külah hat to discourage you from escaping and be organized along with other boys into groups of a hundred, a hundred and fifty, or two hundred called sürü to be brought to Istanbul. Once there, you will be allowed to rest for two or three days. After that, you will be examined for bodily defects, circumcised, converted to Islam and be given a family name in the presence of the Yeniçeri ağası (Head of the Janissaries). Depends on your physique, if you're handsome or talented, you will be sent to the palaces of Iskender Celebi, Galatasaray, Edirne, or Ibrahim Pasha to be trained. If you're an average or a normal child, then you will be registered as an acemi oğlan (trainees, lit. 'Foreign Boys') and will be sent to the Kapıkulu corps to be a soldier. Since in your question you wanted to be a Janissary, i will write down the experience as an acemi oğlan.

Once you become an acemi oğlan, you will pass a two-stage training. First, you will be assigned to a Turkish Muslim family for approximately four to five years. Since you're from the Balkans, you will be assigned to a family in Anatolia so you won't be able to escape. There, you will be taught Turkish language and customs, Islamic practices, and to work for your host family. Every year, the state will also sent someone to check up on you. It's in this stage that you have a risk of death, mostly due of plague. Now, the average age of a devşirme recruit in the late 15th century from the age range of 10 to 15 is 13.5, so you should be aged between 16-19 years old when you finished this training stage.

Once the first training stage has passed, you will be recalled to the barracks in Istanbul to live there, be given military training and taught literacy, principles of governance, basic mathematics and Qur'anic precepts supervised by eunuchs. Discipline was very strict and regulated, as you must abide to the 16 rules of the Janissary corps with the most common punishment be beatings with a falaka (bastinado), though you will still be getting off-steam hours to relax, including participating in various festivals and ceremonies. You will be trained to use various weapons, and will usually train in Ok Meydan area to train archery, musketry, javelin-throwing and swordmanship. Aside from training, you will also be assigned to general tasks like sweeping the city, carrying weight to the city centres, woodchopping, mining, or became a firemen, nightwatcher, or police replacing Janissaries that went out for campaign. Your daily pay would range from 1 to 3 akçes per day in addition to accommodation provided by the state

You will be organized along with your companions into regiments and trained under the same hoca (tutor). Because of that, you will most likely be close to your comrades and companions as you all share similar experiences and being in the same regiment or trained by the same tutor. This training will last for an average of five to six years, after which you along with your companions will be promoted into an operational Janissaries after vacancy was available. Acemi graduation is a solemn one, where graduates marched in a single file, holding the hem of the man in front, then lined up in front of your new Odabaşı (unit head or officer) to be handed a distinct Janissary hat and certificate of acceptance. After which in the evening you will pray and after that you will put on a dolama (coat), marking you as a full-fledged Janissary member. After you graduated, you should be aged about 21 to 25 years old by now

And yes, after you become a full-fledged Janissary you're able to visit your family, honor your birthplace by speaking your native language or wearing your traditional clothing, or if you managed to be promoted into a higher rank, give special patron for your birthplace like Sokullu Mehmet Pasha, or be wished to be buried there like Koca Bey.

If you have additional questions i'll answer them if i'm capable

Sources:

''Becoming a Devşirme " by Gulay Yilmaz

"The Janissaries" by David Nicolle