grammar - How does 最初の何年かは work here?

I'm writing with a japanese penfriend on italki, and I've got a few problems with what she has written me in japanese ^^

For context: Amongst other things, I've written her that I've changed my profession. I successfully finished my studies to become a teacher, but I've changed into the IT-sector because in my country (germany, bavaria) there is no need for teachers on schools anymore for the subjects I've studied.

Now, I haven't written her this backgroundinformation and as far as I can understand, she tries to convince to go for it :D The problem is, as I said, that I don't understand everything she has written me.

So first, the full text: 仕事を始めるとき、最初の何年かはとても大変ですね。でも嫌でも続ける事は、何か自分に意味があります。そういうふうに、日本では言います。だから、本当に自分のしたい事が今できなくても、できるときがくるので、そのときまで粘ってください！かな？？？

What is meant with 最初の何年かは? Does the topicmarker は include the とき phrase as well? => "(Concerning?) The time you start your work, (concerning?) the how many years of the onset it is horrible.

I still have some more questions about this message of hers, but I will put them into separate threads so that there aren't too many on one thread.

Answer

[何年]{なんねん}か means "a few / several years" (≂ [数年]{すうねん})

cf:

[何日]{なんにち}か ≂ [数日]{すうじつ} "a few / several days"
[何人]{なんにん}か ≂ [数人]{すうにん} "a few / several people"
[何回]{なんかい}か ≂ [数回]{すうかい} "a few / several times"

So 最初の何年か means "the first few years", and the は is a topic marker.

仕事を始めるとき、最初の何年かはとても大変ですね。
When you start a new job, the first few years will (usually) be really tough/hard/difficult.

_{p.s. 「数+counter」 sounds a bit more formal than 「何+counter+か」.}