That is going to depend on each individual and the outcome you are working with. People pretty regularly use several at a time, spacing them throughout the day and related to one or two issues. If you are working with too many outcomes or goals at one time, you tend to become too spread out and lose your focus.
That being said, though, if you are going to use multiple paraliminals, be sure to allow 20 minutes to a half hour between listening sessions, so the new energies you are working with have a chance to settle in.
If you start feeling anxious or resentful when you sit down to do a paraliminal, you are probably over-doing it, If this happens, either allow more time between sessions or reduce the number of sessions per day until you regain equilibrium. The discomfort is a sure sign that your other than conscious mind is needing more time to process what you are asking of it.
With regard to English being a second language, if you are finding your listening sessions challenging, build into your stated intention something along the lines of "I easily and effortlessly absorb, integrate and act upon the suggestions and outcomes that are verbalized in English, in this paraliminal." It's amazing what our other than conscious mind is capable of if we give it clear instructions!
All the best!