Learning a second language takes a LOT of practice.
Let's reason it out. When the objective is learning a new vocabulary word in a typical Language Arts Class (in our first language), we require a student to complete approximately five steps per word.
1) Read the word aloud (often repeating after a teacher as a class.)
2) Copy the word (paying close attention to spelling)
3) Read and copy the definition, including part of speech
4) Read and copy an example sentence
5) Use the new word in an original sentence (written and spoken, usually)
Even then, if the student doesn't USE the word effectively in the next few days, they likely never truly absorbed it and aren't able to access the word for use in the future. It went into short term memory, and didn't actually become a part of their vocabulary, or their working language.
Now, in order to become "proficient" with the word, being able to easily access it, the student also needs to hear it spoken by those around them. The community is responsible for their advancement in language. If it's not in the "atmosphere," absorption and fluency is simply highly unlikely.
All this, in a language which we understand regularly, and have a comfortable grasp of the grammar. In a second language, Spanish, somehow, we expect ourselves and our students to read a list of words aloud and then "have them" in long term memory. Be able to use them with a fraction of these steps taken, and usually without anyone in the family supporting them by learning the same vocabulary at the same time.
So! How often do you need to study Spanish? Really, as often as possible.
In hard terms, I always recommend no fewer than 3 times per week of lesson learning and practice, and on the "off days" making sure you receive authentic input and practice.
Each learning session should be about 20 minutes, maybe 25, if your attention span allows for it. This span of time, sitting down, laying out flashcards, finding the book, accessing the audio, and THEN beginning is not considered included in the time.... this span of time moves new tools, or words from short term memory to long term memory, when consistent.
The more often you USE your Spanish to communicate, the more you'll propel yourself forward in your Spanish learning journey. So, say those new words as often as possible, and teach your family your new words!