Should I Take The Domain In Hand or not ?

i have a client that has a website - the website has been done by html and css by someone from his company .

site is not good . now he wants to improve it and make an e-commerce website .

i will do this for him - but i don't have acces to both is domain cpanel and hosting cpanel .

i don't know if i should ask him to give me infos and i change passwords - but if it's like that when the year is finished i can't renew it cause the cpanel has the guy's credit card .

or should i switch the dns to a new registrar and host it in my server - but the dns changing takes time and i probably won't be able to work on the website untill it's switched .

What do you think ?

When I was a developer, what I would do is create the website on my hosting and transfer it over to theirs when I was finished.

Transfers are super easy and it gives the client a peace of mind that you don't have direct access to their entire server.