Maybe you should contact her at the end of this month depending on when exactly you are traveling next month.If she is a touring lady you want to make sure she is available at the time you are requesting.Every one works differently I have gentleman that have already pre-booked for next month it just depends on the agencies process of appointment setting.

several weeks ahead.  Since you are new, it will take some time for the agency to verify you as well as develop a trust with you.  You should have a 2nd and perhaps a 3rd choice in mind in case #1 is unavailable.  Keep in mind, many ladies take off a few days each month when flo visits.

Good luck.

Be upfront with the agency, not sure what kind of travel it is but I have to change my schedule often and I mention that to them up front.  If I am planning a extended date (3-4 hours/dinner) I will contact a provider/agency 3-4 weeks before the trip to check her availability and I tell her that I will be in town but plans change so not to write it in ink.  Roughly 10 days before the trip I will finalize it.  DO NOT go through this routine with back-ups, its a pain in the butt for the girls to do verification so only give that info to the one you sincerely think you will see.

If I'm doing a routine 60 minute visit I'll normally do what I do at home...contact a few days to a week in advance (depending on the provider) to plan.

I am the type that can schedule something 2 years in advance and show up. Just the way I work and it sounds for you as well. Trying to schedule too far in advance (month +) has gotten me poor results. The feedback I've seen here seems to indicate that the ladies view those as "fishing" expeditions with low probabilities of actually occuring.
That said, I would agree with the 2 week window and, especially, having backups. I had pinned all my hopes on one lady last time, ignoring the somewhat flakey hints and ended up having a bottle of wine and flowers all to myself in my hotel room that night.

Unfortunately, the way I have found it works is that it is very easy to schedule way in advance (a month or more) with someone you have seen before, but hard to do with someone you have never seen. Still, it can be done.

First off, since you are traveling there will be a little more understanding of your desire to schedule ahead, so you will be taken more seriously. But even so, you need to follow some steps to be fairly sure things will happen.

Pay attention to how quickly or slowly you get replies - since there is a lot of time, you may have to wait a few days for replies, but if it gets past three days, your email has probably been lost or forgotten. Once you get through screening, make sure you get confirmation of the date and time. No confirmation = no date. If you get a very quick reply, followed by a very slow or no reply, be a little wary. I am not a big fan of sending reminder emails when I have not received any reply - IMO, if they lost one email, why would I expect they would not lose another, even if my reminder does get a reply?

If you are more than three weeks out, reconfirm around a week out - just a quick email to confirm you are still on, nothing has changed at your end. Be clear that you will confirm "Since this is so far out, and I want to be sure we get together, don't want to be a bother, but also don't want to miss a chance to meet you..." or some such.

Be sensitive to the tone and promptness of communication, as well as any specific instructions about how and when to follow up - your plans on that may differ so you need to listen to what you are being told. Some providers/agencies are very professional and organized (same is true for some hobbyists) and this comes through in every communication - if you get that sense, just relax and be thankful. You still should confirm a week ahead so she knows your plans have not changed, but that is it. Then a day ahead or day of the date you will exchange the incall/outcall info.

Finally, have a backup plan, if you really want to see someone. Get screened, ask about availability and tell the backup you will confirm once you are sure of your plans. I defer to other providers as to whether you should actually pick a day or time subject to confirmation a day earlier or not - my preference would be to say that you are looking to meet up on a certain day with no time, to be confirmed day before. That way she will not be obliged to turn away someone at a specific time when you are not sure you will actually show up. Seems more considerate to me.

I cannot stress enough that if you get prompt and clear replies to your initial query and then a clear, quick confirmation of the date, you should be okay. Anything else is iffy - it is not unreasonable to wait a couple of days to reply to a query for a month out, but that could also just indicate disinterest, or disorganization - you cannot know. Early on I worried when the location information did not arrive as early as promised or as early as I thought it should. While that may well mean your date will be late, if you are seeing a well-reviewed, established provider, there is little chance she will stand you up for a date that was confirmed within a week (anything can happen, of course, but it is really unlikely).

Hope that helps,
Zig