You can see the counting of the Omer
here
New Moon – March 22, 14:37
First Quarter – March 30, 19:41
Moon Phases, April 2012
Full Moon – April 6, 19:19
Last Quarter – April 13, 10:50
New Moon – April 21, 07:18
First Quarter – April 29, 09:57
Moon Phases, May 2012
Full Moon – May 6, 03:35
Last Quarter – May 12, 21:47
New Moon – May 20, 23:47
The moon becomes hidden and cannot be seen for approximately two days - or [slightly] less or slightly more - every month: approximately one day before its conjunction with the sun at the end of the month, and one day after its conjunction with the sun, [before] it is sighted in the west in the evening. The first night when the moon is sighted in the west after being hidden is the beginning of the month. Afterwards, 29 days are counted from that day. If the moon is sighted on the night of the thirtieth [day], the thirtieth day will be Rosh Chodesh [of the following month]. If it is not sighted, Rosh Chodesh will be on the thirty-first day, and the thirtieth day will be included in the previous month. There is no need [to sight] the moon on the thirty-first night; whether or not [the moon] is sighted [the new month begins that night]. For there are no lunar months longer than thirty days.