After opening TMUX I first have to reload the configuration file before the Theme is loaded

[ThaDaVos]

Like the title says, after opening TMUX I first have to reload the configuration file before the theme is loaded, this is my configuration file:

set -g mouse on

set -g default-terminal "screen-256color"
set -g default-shell "/bin/bash"

set -g status-left '#{prefix_highlight}'

set -g status-right-length 256

set -g update-environment "DISPLAY SSH_ASKPASS SSH_AGENT_PID SSH_AUTH_SOCK SSH_CONNECTION WINDOWID XAUTHORITY"

bind-key g split-window -c "#{pane_current_path}" -p 50 gitsh
bind - split-window -c "#{pane_current_path}"
bind '"' split-window -c "#{pane_current_path}"
bind | split-window -h -c "#{pane_current_path}"
bind % split-window -h -c "#{pane_current_path}"
bind c new-window -c "#{pane_current_path}"
bind-key r source-file ~/.tmux.conf \; display-message "~/.tmux.conf reloaded"
bind-key M split-window -h "nano ~/.tmux.conf"

bind -n M-Left select-pane -L
bind -n M-Right select-pane -R
bind -n M-Up select-pane -U
bind -n M-Down select-pane -D

# Plugins Config
set-option -g @ssh-split-keep-cwd "true"
set-option -g @ssh-split-no-shell "true"
set-option -g @ssh-split-h-key "S"
set-option -g @ssh-split-v-key "W"

set -g @sidebar-tree-command 'tree -C'
set -g @sidebar-key-t 'nnn,left,60,focus'

set -g @themepack 'powerline/block/cyan'
# Plugins
set -g @plugin 'jimeh/tmux-themepack'
set -g @plugin 'pschmitt/tmux-ssh-split'
set -g @plugin 'tmux-plugins/tmux-yank'
set -g @plugin 'tmux-plugins/tmux-copycat'
set -g @plugin 'tmux-plugins/tmux-logging'
set -g @plugin 'tmux-plugins/tmux-prefix-highlight'
set -g @plugin 'tmux-plugins/tmux-sidebar'

# Initialize TMUX plugin manager (keep this line at the very bottom of tmux.conf)
run '~/.tmux/plugins/tpm/tpm'