In general, it is possible to make changes to a pending reservation request, but it depends on the policies of the specific reservation system or service that you are using. It is recommended that you check the terms and conditions of your reservation, and contact the service provider or booking agent as soon as possible to make any necessary changes. Some reservation systems may allow changes to be made directly online, while others may require you to contact customer service or submit a new request. Keep in mind that there may be fees or restrictions associated with making changes to your reservation, so it's best to review the policies carefully before making any changes.
The length of the booking process can vary depending on several factors such as the complexity of the booking, the type of service being booked, and the availability of the service provider. In some cases, booking can be completed within minutes if the service provider has a simple booking process and the customer has all the necessary information. However, in other cases, it may take several days or even weeks to complete the booking process, particularly for complex services or during peak booking periods. To get a better idea of the booking process for a specific service or provider, it's best to check their website or contact their customer support for more information.