Journals will usually provide details on their websites about their particular peer review processes and timescales.
The time needed for a journal editor to receive all reviewer comments can vary between fields. Economics papers, which tend to be longer than papers in other fields, can take several months to come back from reviewers. Humanities and social sciences papers will also tend to take longer than those in the clinical and life sciences. Shorter manuscripts are much more likely to be returned sooner because they take less time to review.
Delays can occur because reviewers are busy with their own work and may have several reviews to prepare for different journals. Additionally, a manuscript may undergo more than one round of review because reviewers may have additional criticisms or comments after the authors have revised their article. But by recommending your own list of reviewers, you can at least help to speed up the reviewer selection process.
Be aware that holidays may delay peer review. A manuscript submitted in late November will likely not be returned until the following January because of the long Thanksgiving holiday in the United States (late November), and the Christmas and New Year’s holidays (late December) celebrated in Western countries. Other holidays to be aware of are Easter (late March or early April) and the Chinese New Year (January or February).