今日練習何時からありますか？って英語でなんて言うの？

"What time" asks for the time.
You can also say
"What time does practice start today?" or "What time is practice starting today?"

1. This is a basic question which needs no explanation.
2. 'Kick off' is the start of a ball game where the game commences when someone kicks the ball: for example, football or rugby. However, this term is now widely used when talking about the start of any activity, including non sporting activities.
   A: What time does the meeting start?
   B: It kicks off at 2pm.

At what time should I be ready for practice?
This is a formal way to ask for details regarding the times for practice for a specific day.

What times does practice begin?
This is also a casual way to ask someone to clarify the times in which practice is set to begin.

When does practice start?
You are asking for details of when practice is scheduled to begin .

You could also ask:
-When should I make my appearance at practice today?
-When must I rock up for practice?(to " rock up" to arrive at a place or even)
-When does practice kickoff?
-When does practice commence?(formal)

"Around what time does practice start today?"
With this question you are asking for the approximate time at which practice would start.

"At what time does the practice begin?"
This question is asking for the time at which the people involved would start practicing.

The expression "ready to roll"is an English idiom which means something is going to start soon.

The word 'practice' functions both as a noun and as a verb. In the first question, 'practice' has been used as a noun. It has several meanings, but, in this context, it means 'the actual application or use of an idea, belief, or method, as opposed to theories relating to it'.
So, you may say:
What is our practice time today?
or
What time is our practice going to start today?

In the second question, the word 'practice' has been used as a verb in the British spelling and in its present participle tense. It has several meanings, but, in this context, it means to 'regularly perform (an activity) or exercise (a skill) in order to become an expert in it.
So, you may say:
What time shall we start practicing today?

If you would like to ask someone what time practice is that day, you can say something like “what time is practice today?” Or “what time will practice be held today? Any idea?”. This is a simple and straightforward way to ask someone.

1. At what time do you start practising today?
   The preposition "at" is used when you are enquiring/
   asking about the time of an event/meeting.
   "Practising" is a verb and therefore the "letter "s" is
   included. The "c" in "practice" indicates that the
   word is a noun, e.g.
   Hockey practice ended at 6pm.
   As a verb: How long have you been practising hockey?

   2.When does your practice start today?
   The word "when" also means "at what time."