It is good that you have a date that you think will work.
There are a number of things you should be doing next. The most important is register. Then you can get a better feel for if your time line will work.
While that is going on, there are forms to download for your family physician (they are in english), a complete physical, a letter from your rabbi, your birth certificate and so on. So you have lots to do to get to Israel 2 1/2 months before August.
Excerpts from Volunteering Step by Step
http://www.mahal-idf-volunteers.org/abo ... bystep.htm
1. Plan to arrive in Israel at least 2 1/2 months prior to enlisting in the IDF. You can interrupt this period and even shorten it in coordination with the Ministry of Defense; get written confirmation from the MoD in order to avoid misunderstandings.
2. Study this website including the pages Who Can Volunteer?, Your Service in the IDF, Volunteering Step-by-Step, Register Online, FAQ and the external links like the informations for Chayalim Bodedim (Lone Soldiers).
3. Register online
4. The Mahal-IDF-Volunteers.org website will pre-check your qualification and reply within ten days. Note: your qualification is subject to final approval by the IDF Recruitment Bureau.
5. The Mahal-IDF-Volunteers.org website will forward a copy of the reply sent to you to the MoD or the IDF which should handle your case until your enlistment. Expect to be contacted soon by the MoD or the IDF.
Phone the number in our reply to your registration. A dialogue with the MoD is optimal for clarifying open questions, particularly about enlistment and IDF service options.
6. There should be no major problem, but if you encounter any problem, contact us. We will check what is going on and reply.
7. Get a confirmation stating that you are Jewish, signed by a rabbi (Orthodox, Conservative or Reform) residing outside Israel. The confirmation must have a detailed letterhead with the name of the Jewish community, address, phone, fax and email. The exact name of the rabbi must be clearly readable.
There is an alternative to the rabbi’s confirmation; it is more complicated and works only if you can document that you are the child, grandchild or spouse of a confirmed Jewish person.
8. Get the health certificate from your family doctor on the official IDF medical questionnaire - here.
9. Get your original birth certificate and a valid passport for at least about two years.
Find here the country of your passport and check prior to traveling to Israel if you need a visitor's visa to Israel. If you do not need a visa, travel to Israel and get at arrival in Israel a regular visitor's visa B2, valid for three months. Note: if you have to get a visitor's visa prior to traveling to Israel, contact one of the Israeli diplomatic missions. Do not fly over or transit Arab states, Iran or other problematic countries, even if told you can stay during stopovers in the plane.
Note: if you do not speak basic Hebrew, we recommends arriving well before the enlistment to study Hebrew, although most manage with less and even the army ulpan only. For help concerning private Hebrew study programs (ulpanim) and finding a suitable apartment in the period before your enlistment in the IDF - here. Army ulpan - here.