There is no set time on phone calls. See Phone Cards and Phone Calls.
He will write the first real letter the first Sunday that he is in his permanent ship, which could be Sunday, 5 May, but could be 12 May if he is held in P-days longer to wait on additional recruits to arrive and complete P-days and fill his division or his brother division. Once he is in his permanent ship and a Recruit Mail Petty Officer has been trained, he will have Mail Call every evening M-F beginning on about 1-4 DOT. See Letter Writing & Fun Stuff/Questionnaires to send to your Recruit.
He must be at BC at least 3 weeks before the first pay day. Pay days are the 1st and the 15th, so it is very possible that his first pay day will be 1 June (31 May since 1 June is a Saturday) since he will not have been at the RTC 3 full weeks for pay day today or on the 15th; so if you see pay before 1 June, be pleasantly surprised. See When Will the Recruits be Paid? and Information for Spouses.
Join the group, DEP-Leavin for bootcamp in April, to connect with others with loved ones who left that day and may have PIR together.
You may want to join, or at least check out, Boot Camp Moms (and loved ones), Girlfriends, Fiances,andWives of Sailors, PIR Reference Information, and New Members Stop Here. Once you know your SR’s PIR date and/or division number, watch in Boot Camp Moms (and loved ones) and/or at http://www.navyformoms.com/forum/topics/groups-listed-by-pir-date and join the group for that once it has been created. There will be a lot of great information and support for you in those groups. Be sure to check out the Pages (found under the pictures of the Members) and Discussions within the groups. Arrival and What Happens at the RTC within Boot Camp Moms (and loved ones) will let you know what is happening, but you will also want to check out the other Pages in all of the groups.
Since you will have a Corpsman, sometime between now and the end of BC, join HM (Hospital Corpsman) A School in San Antonio.
(Group names within this reply are clickable links. To join a group, click on the group name and after the group page opens, click on "+ Join..." in the upper right.)