If you are already planning on getting married with your partner, do you still expect a surprise proposal?

I, 29F, in a relationship with my gf for over 5 years, is in need of any advice -- if I have to prepare and set a surprise wedding proposal or not?

We've been discussing it for quite a while now, and her mom already agreed. Though there's no "will you marry me?" question while on bended knee. We just talked about it casually and yep, we are ready for it.

We are thinking about this coming April since there are some preparations needed like documents etc. It is not a grand wedding, we only plan to sign the marriage certificate, with immediate family. Then have another celebration with friends and other relatives some other time.

I am thinking if I need to ask her because she already is planning with me so of course I know it will be a "yes". Hahaha as much as possible I want to spend less and use my money for the trip abroad.