Respond as soon as possible. There is no point in delaying a response (or application to a job opening) unless you need some time to polish your resume. Incidentally, this is why you should always keep your resume fairly current.
Some companies do close submissions once their candidate pool is large enough but smart hiring managers won't refuse to consider a candidate who looks like an excellent match but there's little point in waiting unnecessarily. If your field is highly competitive, your profile doesn't stand out or you're desperate for a job then it makes sense to respond/apply as soon as possible.
If you're asking about what's "professional", if you're being cold called by a recruiter I'd suggest that a week or so would be typical. If time is of the essence then the recruiter will mention that. Good employees are often busy employees and recruiters know that: there's no stigma involved with responding "late", unless you're talking several weeks. In that case you'd need to acknowledge the delay and be prepared for the position being filled or applications being closed, but you have nothing to lose by checking.
As an aside, I'd say you're doing too much work. If the position seems interesting and matches your profile then you can just fire off a simple reply to the recruiter asking for more information. Often they'll be scarce with details in their initial contact and will have a more in-depth job description they can send you. Some will want to call you instead and that's also normal. First calls like that should not be considered formal interviews so you don't need to prepare for them. The recruiter will just explain some of the aspects of the position and might ask about your experience or work history to see if they match. If you're still interested in the position after that extra information, then you can start researching the company and formally apply as a candidate. This has the advantage of quickly putting you on the recruiter's radar so you don't risk missing out on time-sensitive opportunities.
To quote Alison Green who I previously quoted in my answer to a related question:
Apply as soon as you have time to do it well, and don’t worry about the timing.